I'm not a 305 guy but after I burned a piston in my 350 I had in my 86 GMC, my cousin give me a Vortec 305 . I installed a Performer intake , headers and the original Qjet. For an engine that was just supposed to get me back and forth to work temporarily, it's been 10 years and I couldn't be happier.

@xmo552

20 күн бұрын

Same story in my brother's 4 door 68 Impala.

I've always suspected that the reason the 305 in particular responds so well to the TPI system is because of the ram effect of the long runner TPI manifold. The TPI is essentially a very long runner tunnel ram laid out on its side. You can't rely on a big bore and big valves for cylinder filling with a 305 like you can with a big bore block, but the ram effect of the TPI manifold helps to overcome the small bore and small valves as a breathing restriction, at least within a certain RPM range where it was designed to maximize that effect, which is right in the range where the TPI ran away from the Qjet motor in your test.

@mistabone3899

10 ай бұрын

I had an 86 TPI WS6 with the "peanut" cam for emissions.

@CzechSixTv

9 ай бұрын

Tunnel rams give air as straight a path as possible from plenum to intake valves. Their height, at least on traditional carb versions, is just a side effect of reducing runner angles. Like individual throttle bodies, they are designed for high rpm power. A stock TPI intake is the exact opposite. Runners in the lower intake go across the engine and are almost parallel to the lifter valley. In effect it is a low rise dual plane intake with really long(small cross section) runners. TPI was designed from the git to produce lots of low/mid rpm torque. Compare a stock TPI lower intake to a Holley Stealth Ram lower intake and you'll see the difference is night and day.

@buzzwaldron6195

Ай бұрын

I suspect the 305 short blocks weren't really the same... the one a 145 netHP LQ4 305 base level flat tappet cam, the other a 230 netHP TPI 305 version of L69 but with the TPI roller cam...

@xmo552

20 күн бұрын

Well the tpi WAS designed for the 305....

I bet you the qjet will shine brighter(er) on a better intake manifold

@ryurc3033

9 ай бұрын

Nice spread bore dual plane aluminum high rise.......I agree.

TPI Induction has more runner length / Volume and a large raised open plenum (Think air gap). This would appear to be an immediate advantage over a low rise dual plane, and perhaps explain the position of the torque peak.

@johnpye7177

10 ай бұрын

I raised a dual plain with a 3/4open spacer. Proformer intake. I do t know what it did but it likes it.

@CS-oe8og

10 ай бұрын

I believe it to be runner length as well. Great test though.

The performer RPM intake is magic.

The dry, long runner TPI intake and it's "precise" port injection made the difference. That Dinosaur cast Fe intake and equally woeful Q-Jet left a lot to be desired.

I'd love to see you collaborate with a Q-Jet specialist like Cliff Ruggles next time you use one in a A/B test, I'm sure great information would come out of it :) Love the videos, thanks for everything !!

Becuase TPI, that's why. GM figured out how to get big power from modest heads using just a TPI's good looks and runner length.

The difference is that the stock versions of this engine is the reason why GM went from carbs to EFI. They always stated that the switch was for more reliable running engines along with better operating at colder and hotter temperatures and better fuel economy also better control over the vehicle. This was of course better selling points to the bean counters, but what sold the cars and trucks with these engines over the previous carburetor equipped engines was of course increased horsepower out put. The 305 of the carburetor version were great sold engines that were great alternative for the 350 for people on budgets, but with the addition of fuel injection GM was finally able to make the realization of the 1957 fuel injected 283 engine with the affordability and reliability of the carburetor 305 or 350 giving the consumer a choice that the other companies weren’t. Even though they were advertised at a certain output we knew that it was actually a little more. You can thank the insurance companies for this reason.

86 Z28 ran 13.4s with 305 world heads, isky cam, Hughes 2200 stall Was pretty solid in the pre-LS days

@MasterWitchDoctor

3 ай бұрын

my '87 Monte Carlo K/SA stock eliminator is an 11.60s car running 118 mph with 081 stock heads with nothing more than a multi angle valve job. The intake and carb are stock 14057053 and a Barry Grant (while he was still in business) modified L82 quadrajet. My engine is making 419 horsepower and Im certain that Richard probably use a 416 casting and not an 081 center bolt head. The 081 305 head is by far the best non vortec 305 head Chevrolet cast and @ .400 lift actually out flows any 350 non vortec head with a 1.94 inch intake valve. I can easily get 260 hp out of an L69 305 with an 081 head with nothing more than a 5 angle valve job and orange Z28 springs. Give me a custom ground hydraulic roller cam with 220 - 224 intake duration (a 305 is a whole more more sensitive to cam timing than a 350 is) and 228 - 232 exhaust with a 4/7 swap and 1.5 ratio roller rockers,130 lbs of seat pressure @ 1.75 inches, and ill show you a 305 with stock ports, stock intake, and quadrajet making 325 hp with all the accessories attached.

I always loved the 305 very underrated

I think a different intake manifold would wake the q-jet combo up. Sounds like a great test, Richard! ....something tells me, he has already done it :)

@54inches

10 ай бұрын

Same is true for the TPI and it has already been done too.

@chrisreynolds6520

10 ай бұрын

Looking at the power curve, I believe the engine he tested with the Q-Jet had the peanut 178/194 @ 0.050 cam and the later TPI he tested had the 202/207 @ 0.050 L98 cam. Substantial difference in cam timing between different years and applications on the 305s.

@54inches

10 ай бұрын

Not sure why you're responding to me, it's his test.@@chrisreynolds6520

@adammcilmoyl4278

10 ай бұрын

That factory Qjet manifold is actually pretty good, it definitely wasn't the bottleneck in this test. It's not on the level of something like an RPM, but it's at least as good as a basic Performer. Lots of testing shows those manifolds to make as much hp as a Performer, and usually more torque too. They're a better manifold than they get credit for.

@chrisreynolds6520

10 ай бұрын

@@adammcilmoyl4278 I saw nearly 20 hp switching to the RPM from a stock aluminum Q-Jet manifold on a stock 305 long block in my 83 G20. The stock manifold strangled a ~200 hp engine. The RPM gained power everywhere. More to the RPM than just flow. The runners are longer and straighter which helps add torque. The plugs were more evenly colored as well, indicating a better air/fuel mixture distribution and a cleaner burn.

Perfect video for the day. My neighbor just gave me the 60k 305 mile engine out of his El Camino, and I want to use it for a swap.

Hey Richard ! Great video comparison... My 85 Fbody was rebuilt 20 y ago and I went with smog legal Holley intake, but had to keep the electronic Quadrajet - RV cam and banks catback exhaust system. Power went up enough to put the car at high 6's on 0-60 - where it was low 9's before - or about 2+s faster :))) Now I am considering the Lsx, but then I saw your video about cheap M90 supercharger ---wow - what a gem - thanks for that! Happy New Year too.

The difference is the TPI manifold's superior ability to fill the cylinders in the rpm range of that cam

I am a 305 Guy! No room in the garage for an engine swap, so the 305 is a keeper. Runner length and volume is your friend with the TPI.

The difference there between the two stock engines was the cam and the intake manifold runner length and the fuel atomization differences of carburation versus fuel injection. Also the compression ratio and valve sizes were probably different. There's plenty of differences that can play a role in these two dyno results.

cam and intake perfectly optimized in the tuned port version. carb and manifold needed different cam lobe separation

Right on

Love it Your the one also I miss you 4cl Hondas videos I hope get some inf from you

The factory cast iron Intake manifold used must be a major air flow restriction. The carb may have something to do with it also. If I had to pick the major factor it’s that intake manifold.

@MarcBchannel

3 ай бұрын

The manifold definitely, not the carb. That qjet flows around 750cfm. Plenty of carb

I think it will be very interesting comparing a 305 with 307 with the same equipment .

I replaced the stock iron intake Qjet with a Edelbrock performer 600 holley on my 1985 pickup 305 and I couldn't believe the extra performance. I was very happy.

If I had to guess, I'd say the larger manifold volume in slight combination with the fuel injection helped make up that power gap you're seeing, it could also be the jets are a little small on that q-jet for that long block and manifold but that's purely speculation

I think it boils down to runner length in the intake track. the Q-jet manifold has shorter runners than the TPI. which changes the harmonics of the pressure wave during induction. those tpi runners are about as long as a tunnel ram. I don't know if it was a factory manifold or what year, but some of those just suck really bad. the best on that I know of is the factory L-82 aluminum corvette manifold 3997771 and 340261 from Camaros, and the 458520 from corvettes.

Don't forget outside of the US we can't go to the wrecking yard for a 350. Also there are a lot of 305 boat motors outside US

@Richard Holdener this other big name channel built up the 305 to 385hp then put nitrous 2 stages when they hit it with the 300 shot it broke a piston land. They didn't gap rings it was untouched bottom end. But with the 250 it made well over 600hp. If you still got it see how much you can spray in it

@timtodd6830

9 ай бұрын

Pretty sure he knows those guys 😉

@corvettefever360

7 ай бұрын

Yep he definitely knows those guys. Lol!

The 40HP difference was largely spelled out in the L69HO vs the LG4 LO cams, which was 190hp vs 155hp respectively. A 204/214 or 214/224 cam is the best money under $200 you can spend on a 305 in your car if you have the 179/195 cam in it. I had an LG4 in my Astro with a 204/214 in it, was pretty darn fun. :) I'd be sticking a performer RPM or a stealth ram on probably just for ease of service over the TPI. Oh, and power :) Those aftermarket TPI parts are collectors items these days from what I've heard. Lingenfelter uppers or AS&M runners go for bank these days.

@timtodd6830

9 ай бұрын

He said both engines were roller cam tpi originally. If the 267hp was out of a manual trans car the cam was (iirc) a 207/214 duration 414/427 lift. The automatic cars had a roller version of the 179/195 cam you mentioned. Basically same concept as the original q-jet L69/LG4.

@MasterWitchDoctor

3 ай бұрын

oke let med enlighten you on the cam used in the LG4 and L69. They use the same 14093643 cam 202 duration intake x .403 lift and 207 exhaust x .415 lift with a 114.5 lobe separation. This is a computer controlled cam much like the 1990 - 1992 L98 10111773 which is pretty much the same cam only difference being is its a hydraulic roller with .413 lift intake and .428 lift exhaust.

@thetriode

3 ай бұрын

Citations please. Every source I've seen indicates that the LO cam was the peanut cam. I've taken a few apart in my day, and they were the peanut cam. @@MasterWitchDoctor

@MasterWitchDoctor

3 ай бұрын

@@thetriode try looking up the part number in a Chevrolet Microfiche like my buddy Larry Hoover did at Alexander Chevrolet where he works in the parts department. I race an '87 Monte Carlo SS in NHRA Stock Eliminator K/SA so I may know something about it.

@thetriode

3 ай бұрын

@@MasterWitchDoctor a mcss would be a l69.

One was an automatic car camshaft. The other was a 5 speed car camshaft. That's my guess, yes they were different to some extent in the 87-92 roller cam TPI 305s.

@claypaul2012

10 ай бұрын

Lb9 cam was pretty similar to the vortec 350 camshaft

@bluecollarhotrods9781

10 ай бұрын

@@claypaul2012 90-92 305 & 350 = same cam. The 87-89 had the "peanut" cam. Also used in the TBI engines. It's only 179 degrees of intake duration.

@claypaul2012

10 ай бұрын

@@bluecollarhotrods9781 tpi and g92 cars did not get a peanut cam

@bluecollarhotrods9781

10 ай бұрын

@@claypaul2012 The 87-89 305 TPI automatic cars (non G92) absolutely did.

@claypaul2012

10 ай бұрын

@@bluecollarhotrods9781 mine is t5 and g92

That tpi plenum has more available air than the low rise dual plane intake fo sho. Shoulda tried a 2" carb spacer before modifying to see if giving the intake more volume would balance the difference between the 2. Thanks Rich!! Keep testing!!

@richardholdener1727

10 ай бұрын

it didn't need more plenum volume

Great info. I used to have a Dart headed 305 with a Summit cam exhaust etc, in my 1979 Camaro went 15.1. But I thought it could have been better, so it got a 150 shot of N.O.S. went in the 13's not bad for a 305.

@hayden6056

10 ай бұрын

What fuel do you need to not strip a ring land at 15:1 with a 150 shot?

@rajcam80

10 ай бұрын

@@hayden6056 15.1 in the quarter sorry for the not clarification.

@hayden6056

10 ай бұрын

All good I was just like Jesus that's big comp haha.

When I was a Pontiac Technician in the 80's and 90's we would race Qjet HO 305's against TPI 305's and the HO's would usually win. Also, Qjets are at minimum 750 CFM. I am guessing the camshaft in the stock TPI block is more optimal with computerized fuel delivery and spark timing. The carburated HO's had computer comand control Qjets and spark timing. The Qjet 305 you tested had none of these.

I'm sure the intake plays a part, but aside from that it's gotta be a tuning issue. The qjet is not lacking in cfm capability at all for an engine that size. They've been on 600 hp race cars, and my ~375 hp 350 runs exactly how it did with a holley on it. It's just way more drivable now, too 😂

@jacobnorth8642

10 ай бұрын

I put a 91 305 firebird motor (auto) in my 71 chevelle because it was cheaper then a tow dolley when i moved. My stock 350 was trashed, it had one of those 2psp "economy" intakes from late 70/ early 80s and a stock mechanical secondaries qjet, stock exhaust manifolds, small 2 od dual pipes, quit mufflers. I put a summit stage1 roller cam, used performer, headers, 2 id y pipe kit with summit magnaflow copies, car burns out now without using any clutch pop (255/60 r15 tires) with lunchbox no slip. Very happy with my qjet 305 for price, lacks some high end but didn't want to change heads and valve springs. Wish i was getting 25mph, if i pass a gas station I'm walking... need a 2x4 under gas pedal i guess...

TPI I believe was originally designed FOR the 305 from what I have read on the internet (we all know what thats worth). But it makes sense. We all know the tpi chokes at higher RPM but even on the stock TPI 350 and 305 cars I have driven, the 305s hang on longer and just seem happier and hang on longer. You can even see in these graphs, that lb9 never falls off a cliff all the way to 5000 like the l98 does right around 4500. It seems that the port size and velocity was tuned perfectly for the 305 that it gets the perfect amount of cylinder filling and gets all you are gonna get from that engine, with that cam, with those heads. Obviously goes out the window whem modified. But if both long blocks were truly the same, thats the only thing that makes sense. The LB9 honestly is just a display of impressive engineering from GM. It was such a step up from any 305 before it. Also always thought it was funny that the manual LB9 cars (230 Hp version) got within 15 HP of the hottest L98 (245 Hp). The 350 has more torque and area under the curve but not as much as there should be. More evidence the system was really designed for the 305 and adapted to the 350 as well.

If the carb is tuned right then it's all in the manifold. Runner length and volume. There may be a slight variance in cam spec, but my guess is intake manifold.

At that HP/TQ/Ci and the RPM levels they are produced at by the stock engine combo the TP runners are simply a better match than the dual plane. Any aftermarket dual plane intake would lose even more TQ on the stock combo and at that HP level not make any more peak HP than the stock dual plane either. Probably a very interesting test would be to use the TP intake on either modified combo.

A flow bench test of both manifolds would answer the question I'm sure. And its not just a flow issue, its a velocity issue as well. But, I'm also sure you know that already...😉 Interesting test! 👍

@greenbassboosts8872

10 ай бұрын

Runner length difference too to some extent I'm sure

More questions than answers!

Im not a mechanic but I'm hapy with any 305 vids.

Looking at the curves I believe there is a difference in camshaft between the two. From the flow numbers I could find the intake is definitely a restriction if the cam lift was over .400 but I’m not sure if it was enough of a restriction to make THAT much of a difference.

The Tuned Port uses a ramming effect with its long columns of air in each intake tract. The high port energy comes from inertia of a narrow column of air, but it has some decent mass due to the long length. At the RPM it is "tuned" for it acts almost like a tiny bit of boost. I have heard claims of 1-3 psi of positive intake pressure at torque peak, but given the small cross sectional area this free boost turns into a restriction past about 4500 rpm in stock form. The Q-jet has no such fancy ramming and therefore less output. With 20 degrees more cam timing in each I think we would see the tpi fall behind. As some others pointed out there was likely a cam and head difference as well.

@richardholdener1727

10 ай бұрын

please do a search for reflected wave (and the other two forms of charge filling associated with intake design) Inertial ram and Helmholtz Resonance

@mistabone3899

10 ай бұрын

@@richardholdener1727 Like the NACA test MIT did and published in 1943 or 1944,

@kenrolt8072

3 ай бұрын

@@richardholdener1727 As in Morrison & Smith book on the scientific design of intake and exhaust systems.

I'll keep my q-jet 305 the way it came from the factory, it's fine. Pretty sure it's faster than my 2V Cleveland in 1/4 mile. Runs like a watch, smooth as silk.

The qjet manifold has tighter turns than the tpi manifold so it is more inefficient. The tpi probably has better fuel distribution also. Put the qjet on an intake with straighter runners and more volume and it'll be closer to the tbi.

My guess is that the hot plate in the manifold under the Qjet was, well, hot.

First 👍's up Richard thank you for sharing 😊

Has to be a cam and or head difference. Everyone says that the TPI setup is so hard to make power up top with. I'm in agreement with the peanut cam theory. I know that even the factory Qjet intake manifold will equal or beat a TPI for hp. The TPI is unbeatable for low and mid range torque.

@Sabe53

17 сағат бұрын

I've always said GM missed the boat by not putting, offering TPI on their 4X4 trucks and Blazers. Way better truck engines.

The carb 305 originally had a crappier cam and made way less HP than the tuned port motor. depending on the year. Tuned port motor's made as much as 230 hp. and with the carb, as low as 135..... Infact. If you put the quadrajet on the tpi block. it probably would make more power than the tpi did.

I think the answer lies in the tuned port length of the runners that gives high torque a dual-plane manifold is much shorter and doesn't have the velocity of the long tube intake

they most likely had different stock cams. One was probably a truck cam vs a police package or z/28 cam. that's my guess anyway.

Difference in intake manifold is part of it. Fuel distribution may not have been as balanced with the 4 bbl intake would be the another factor.

I think the difference on the stockers is the fuel injection seems to be cooling the air better than the carb in this particular setup. Just a guess.

I remember back in the 80's that those factory Q-Jet manifold was horrible for power production. I do not put all of the blame on the Q-Jet, especially the one you had from Murphy as being the best version

Try a Holley 80555C and see how it does. It is a spread bore, and is vacuum secondary.

The one that was run as a 305 TPI was probably an engine for a G92 car. Despite still being a LB9, the engines in the G92 cars had a slightly hotter cam with a 500rpm bump in the redline. So no, I do not suspect they were the same long block and I do suspect that cam difference made up the bulk of that 40hp disparity.

@timtodd6830

8 ай бұрын

Yes it was definitely the cam.

That is exactly what the TPI was designed for.. Similarly, it is not easy to get 400 HP or more with that TPI..

The only thing I can think of Richard is that maybe there was some sort of weird mismatch with the cam and intake and carburetor wasn’t getting all the vacuum signal it needed.

Some 5 speed 305s(and auto 350s) had 207/213 cam. Most Automatic 305s had a roller version of tbi cam 178ish

@chrisreynolds6520

10 ай бұрын

All 90+ speed density 305s and 350s had the bigger cam. The lower power 305 is because of the LG4/L03 exhaust manifolds and single cat.

@timtodd6830

9 ай бұрын

Yep

Had you used a set of either stock Siamese runners or something Like slp Siamese runners the tpi would have made more torque and the same hp as the rpm intake and carb or maybe more. Back in late 90s when these were popular we saw upwards of 75whp increase on a 5.7 sbe stock ported l98 heads mild cam car by porting the lower intake upper runner area about 1.5 inches into the port. Then the runners opening them up also so creating a break in the intake so it can suck from both upper runner tubes. We turned these “truck” intakes and turned them into 6600 rpm capable sleepers. My 1992 formula was stomping the hell out of the newer lt1 cars mod for mod with a combo like that. I eventually went to a Holley stealth ram on the car when did a single turbo but that l98 intake was a very good setup when ported correctly. I still own that car today along with my 1994 z28 and 2017 zl1.

@richardholdener1727

10 ай бұрын

we had big tube tpis runners and also tried siamezed runners (they make less torque)

Ram Effect Tuning, like the old Mopars. There is a MIT NACA paper on the subject 1943 or 44. Same as a 2.25" CAI long intake vs a 3" SRI on a Honda, like you've played with before.

@richardholdener1727

10 ай бұрын

three forms of charge filling associated with intake design, etc....

I’d say it’s the port velocity difference in the intake runner designs.

1:38 before this starts in your intro I just have to say yes, you can always jump up to the 350 and it’s more power but in today’s market today’s economy, the 305 sips a little less of that expensive liquid gold in the Quadra jet can actually get pretty good fuel economy because of its design. Also, when you come to dealing with Quadra jet’s, there were several different versions he had performance versions for some of the big block engines. I think we’re up around 700 CFM 650 and I know they had some smaller ones that were like 450 and 500 so if you use the smaller Quadra jet on a 305 and you run just on your primaries never opening the secondaries, you get pretty good fuel mileage know if you put a stock Quadra jet from what that particular engine would’ve come out of which would’ve been a GEN three Camaro. Usually it would’ve had a smaller I think 500 CFM carburetor versus the larger big block intended Quadra jets would I do know for a fact is that you can takeoff the intake from both of those set ups and put you a good Edelbrock rpm air gap in a 650 dual feed, double pumper and a little exhaust get rid of the mechanical fan and you an electric fan and it really wakes up that little engine. I’m sorry to say I was once a puppy kick but I’ve come to respect the little, 305

The tpi was designed for the 305 so it stands to reason why 305tpi performs so well

Back in 1985 I did a test of my own at a Chevy dealer near Seattle WA, with 2 - 1985❤ camaros ( new) one Tpi and the other thoutle body. They may have been similar on paper although the tpi outshines the other ran much better, layer tire better, acceleration was way better and overall performance it was tpi hands down Double k from western pa

@richardholdener1727

9 ай бұрын

TPI vs TBI is not as contest-big difference in rated power output

I believe the factory cam is optimized for the TPI runner length. The Q jet manifold has shorter runners than the TPI and the air flows through it differently.

@grandmasmalibu

10 ай бұрын

305 TPI used the same cam as the QJet-equipped L-69 HO 305. Even when they went to a roller cam in the 87-up motors it was nearly a clone of the L-69's flat tappet cam. From memory, the specs were something like 202/206* @ .050 on a 115* LSA. Even the lift was almost identical between the flat tappet and roller TPI cams. .403/.415". The cam profiles were around before the TPI engines even existed.

@chrisreynolds6520

10 ай бұрын

​@@grandmasmalibu The 86 TPI cam was 178/194 @ 0.050 and 0.350/0.385 lift on a 109 LSA.

@timtodd6830

8 ай бұрын

The automatic cars had the LG4 cam and the manual cars had the L69 in 86 and an even bigger roller cam in 87-92.

@chrisreynolds6520

8 ай бұрын

@@timtodd6830 ALL 85 305 TPIs came with the L69 cam. ALL 86 305 TPI engines had the peanut cam from GM, part number 14094097. I have had several of them apart with manual transmissions at lower mileage and they had the small cam. The larger cam for manuals came with the roller cam upgrade in 87. The autos had the LG4/L03 roller cam and the manuals had the L98 cam. At some point GM added the larger outlet manifolds and dual cats to the 350. At that point the manual transmission 305s could also come with the better exhaust as an option. In 1990 and beyond ALL 305s had the L98 cam. The higher HP used the L98s larger outlet exhaust manifolds and dual cat setup. The lower HP version had the L03 manifolds and single cat. All the variations between the various options is why some of the LB9s were dogs and others that seemed identical would fly. I had a 1990 LB9 G92 5spd car that ran 13.90s @ 101 mph bone stock. I also had a 1986 LB9/Manual that was a dog until I put a mild 218/218 @ 0.050 cam and headers on it.

@chrisreynolds6520

8 ай бұрын

@@timtodd6830 In the older days when these cars were all factory, the easiest way to tell which cam the F-car 305 came with was to look at the tachometer. If the car has the stock cluster, the redline on the peanut cam starts at 5K. On the hotter cam it starts at 5,500.

Intake runner length on the TPI is much greater than the cast iron version. Also, you didn't mention casting numbers on the stock heads. were they the same valve size & combustion chamber volume? Higher compression ratio on the TPI motor? It would be neat to get ahold of a Smokey Yunik SY-1 intake and see how that compares to current technology. I have a buddy that has one, but hasn't put it on anything for a very long time.

I know you know this but HP = Torque x RPM/5250. Less torque for a given rpm means less HP. For the base numbers, the longer TPI runners simply produced more torque in the 2500-5000 rpm range. That's what the TPI system was designed to do.

@richardholdener1727

9 ай бұрын

5252

The factory Heads and Gaskets make the difference and why the Qjet setup was lower HP from the factory!

I'm thinking the stock cam may have been different between the two engines.

@danr9584

2 ай бұрын

I can’t believe how big the difference is. For carbed 305s, they had the LG4 or l69 which also had better cam and higher compression, and would have been comparable to the LB9 TPI. I wonder if someone had swapped in a base LG4 into that car at some point an lO3 with the terrible swirl port heads.

Always like you info, thanks do u know any stock eliminator guys ? How are they running low 11nz,do you know what they run their rpm up to? in stock

Any chance it was formerly a TBI motor with the "high swirl" intake ports? or did they ever use those heads on TPI motors? They definitely had the LG4 cam on certain 305 TPI motor years, which might explain the carbureted motor making so much less top end and midrange. Otherwise, if not some timing or fuel mixture issue, or just a crappy intake manifold, I'd have guess that this Q-jet didn't open the barrels fully, like some stock ones that are configured for low emissions and power.

My guess is the carb engine had the 178/194 @ 0.050 peanut cam and the TPI engine you tested had the 202/207 grind. There was a piston difference, some were dished and others flat tops. A Performer RPM was worth 20-30 hp over stock as well.

@lb9gta307

10 ай бұрын

Peanut cam engines (carb, TBI, TPI and both roller and flat tappet) make peak power at 4k rpm. I haven't seen one still gain up to 4500 like this test engine.

@chrisreynolds6520

10 ай бұрын

@@lb9gta307 My 310 (0.030 over 305) made peak at 4,700 rpm with the peanut cam and 187s. Edelbrock 3704 manifold bored to 2", 454 TBI unit and old design really long tube Thorley Tri-Ys for a G20 van that had the collectors equal with the 700r4 crossmember. I made 197 whp and 284 wtq with it.

@lb9gta307

10 ай бұрын

@@chrisreynolds6520 this was a stock engine

@chrisreynolds6520

10 ай бұрын

@@lb9gta307 With headers and a 750cfm Q-Jet, basically a 1987 LG4 that was freed up a bit. GM rated the 87 LG4s power peak at 4,400 rpm.

@mistabone3899

10 ай бұрын

I think my 86 5.0 WS6 peanut cammed motor peaked at 3800 on a chassis dyno, damn B&W 9 bolt rear end

We'll discuss on your live this evening regarding the huge difference in power. if you ever want to sell the TPI set-up let me know.

@richardholdener1727

10 ай бұрын

it was cam

@ahotmess2261

10 ай бұрын

@richardholdener1727 I figured it would have been more the longer runner TPI intake over the Qjet dual plane and fuel injection than it was the 2 cams although the one cam did have dramatically more lift like 50 thou'ish, and 3 more degree's of LSA. Bumpsticks FTW

Looks like 305s prefer long runners. Though it would be interesting to see the qjet with a performer rpm intake vs the tpi to see how close the numbers would have been.

TPI was a good set up at the time and the stock 4bbl intake wasn’t very good. 42 hp gain from the swap isn’t a stretch though I was expecting better from the cast/Qjet set up.

GM put swirl port heads on TBI-equipped engines back then. Maybe the TPI heads just don't work well with wet flow intakes.

I'd agree, if you used a Stealth or RPM manifold it would close the gaps.

Totally open up the pleum on the stock intake manifold....then dyno

@richardholdener1727

9 ай бұрын

the plenum isn't the issue

There are tons of 305's running successfully in stoc eliminator

i;m going with the consensus and go with the intake manifolds look at the torque difference down low

I think it's a combination of the stock truck engine intake manifold, and the TPI cam profile. I bet it would of picked up at least half the missing power with almost any modern dual plane intake.

TPI was made/optimized for the 305

Would the tpi runner length and shape effect the flow and volume of air feeding cylinders?

It seems to me it has to be either compression related 76 cc heads vs 56 cc, or a big difference in the stock cam profiles or both. The cast iron intake runners are extremely small, so maybe that came into play as well. But I am betting more on a compression difference.

Intake manifold runner length? Timing curve or total timing? Was the Q-jet opening all the way?

@richardholdener1727

10 ай бұрын

timing adjusted to max power, q-jet was opening all the way (described in the vid)

The intake manifold can better fill the cylinders above 3000 RPM. We can skip the part about atomizing fuel better.

Would love to see a shootout of a 059 vs the 175 head. Weather it would be worth your dollar or not for a set of heads vs guide cutting and screw in studs on the 059s.

In my opinion- the Q jet has a much bigger secondary. That 305 just cannot flow a 750cfm carb where you start with 1/3 of the air down low and get the other 2/3 all at once. A great addition would be a 650 cfm square bore against the Q jet. That's the whole game.

@richardholdener1727

9 ай бұрын

that is not how a carb works

@canam111979

9 ай бұрын

@@richardholdener1727 I'm surprised to hear such a ignorant reply. I'll assume I didn't articulate my point well enough. A 305 cannot breath well enough to utilize a 750 carb and stock intake. This issue is resolved greatly using TPI for obvious reasons.

@timtodd6830

8 ай бұрын

The factory cams were different in these two 305’s.

TPI had longer runners and moved more air than the little q jet and cast manifold. I wonder if a 1” spacer would do wonders on the q jet combo? Or even better an air gap intake?

If you happen to have a tpi 305 with roller cam or perhaps an early 305 with 601 heads or even a vortec 5.0 it could be a budget sleeper. The tbi engines sometimes had okay compression but the high swirl heads don't flow and it might be okay for a 305 but you will probably never see 400 na HP on the tbi heads.

@RickBaconsAdventures

10 ай бұрын

I put flat tops in my swirl port truck and worked on the PROM and it really woke up. Not a race car but it gets 18-19 mpg on the interstate. Doesn't really rev past 4500 but I have other cars for that!

Could it be heat soak in the cast iron manifold? The TPI has a pretty good gap above the valley and is made of aluminum, so maybe the effect on it is less? The Q-Jet has plenty of airflow for a 350, I’m sure Richard tuned both spot on, and the dual plane design in aluminum is a proven design. The only other thing I’m induction I can think of is the quality of the casting? Just some guesses

I like it when you do the weird stuff! turbo magnum! turbo magnum! turbo magnum!

An iron intake is the obvious culprit. TPI breathes a hell of a lot better than the smog intake. With an adapter, I'm fairly sure that the Q-jet would have been close to the numbers on the air gap intake.

I'd like to see a stock 305 HO from an early Monty Carlo SS on the dyno.I think they were rated at 195 HP. Early as in the ones without overdrive.

@irocitZ

7 ай бұрын

I'm curious myself, I have a L69 H.O in my 84 Camaro Z28. I wonder if Chevy played with the numbers in the 80s the way they did back in the heyday? With just some minor stuff it's a pretty decent running car.

305 ho engines had different cam and aluminum 4bbl intake and flat top pistons

I wonder if playing with different lifter preloads might have gained something. I recently had a situation where adding more preload to a ford 302 with a healthy hyd roller cam gained about 1000 usable rpm. It made the cam act so much bigger that the power brake assist was noticeably worse after resetting the preload. That was the only change we made.

@richardholdener1727

10 ай бұрын

1000 rpm?

its all in the intake manifold

Compression ratio? If not, better flow, intake charge velocity, and even air and fuel distribution.

All else being the same, it has to be the intake manifold. I'm doubting the QJet would have caused the issues. The TPI manifold can make a lot of torque at the mid-range. The old cast iron QJet manifold has shorter runners and is very flat. Lots of angles which doesn't allow the air intake charge to settle down and smooth out. The TPI just lets things fly up to the point where it starts limiting air flow on the top end.

The O2 sensor and accompanying CPU tuning on the TPI. Not, camshaft or plenum length etc etc etc... That would not make that big of a jump.

@richardholdener1727

10 ай бұрын

there is no O2 and CPU tuning-Both the AF and timing were dialed in for each combo til it made max power

The two stock motors had to have different cams.