Differences with the TPI and TBI
11-03-2000, 07:41 AM
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Differences with the TPI and TBI
Originally posted by Pablo:
Exhaust and heads
We all know the TPI cars have way better exhaust manifolds and y pipes and catbacks
and it was suspected the heads were different
WELL, I have proof today
Our head casting number is 14102187, swirl port heads, extremely restrictive
a friend of mine (MrJ) with a 91 Trans am LB9 auto who runs some pretty fast times with very few mods (14.9@93) gave me his head casting number
#14101081
so its pretty much a given that L03 heads stink I think swapping to these tpi heads or the earlier #416 305 H.O. heads would unleash more than a few tenths.
Id really like to see someone bolt these on or the earlier #416's and just get headers and open element and post some times. I wouldnt be surprised if they were faster or the same times as an LB9 auto with headers and open element
either heads, the 081's or the 416's are a dime a dozen so why not look for a decent set and bolt em on?
Exhaust and heads
We all know the TPI cars have way better exhaust manifolds and y pipes and catbacks
and it was suspected the heads were different
WELL, I have proof today
Our head casting number is 14102187, swirl port heads, extremely restrictive
a friend of mine (MrJ) with a 91 Trans am LB9 auto who runs some pretty fast times with very few mods (14.9@93) gave me his head casting number
#14101081
so its pretty much a given that L03 heads stink I think swapping to these tpi heads or the earlier #416 305 H.O. heads would unleash more than a few tenths.
Id really like to see someone bolt these on or the earlier #416's and just get headers and open element and post some times. I wouldnt be surprised if they were faster or the same times as an LB9 auto with headers and open element
either heads, the 081's or the 416's are a dime a dozen so why not look for a decent set and bolt em on?
Plus, is there a difference between 305 TPI heads, and 350 TPI heads?? Could I put 350 heads on my 305 block??
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Godti
'89 Trans Am (Red)
305 TBI 5spd
11-03-2000, 08:04 AM
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I'm pretty sure that these TPI heads are (with the exception of not being aluminum) the same as the vette heads of the time. There was a little bit of info on them a year or so ago in hot rod magazine's 'junkyard jewel' budget buildup. They used the TPI heads as the first try, later upgrading to vortecs.
Mike
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11-03-2000, 09:23 AM
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305 TPI heads are not the same as Corvette (or any 350 head for that matter). All 305s got 1.84" Intake Valves. TPI 350 (Aluminum Corvette and Iron F-body) had 1.94" Intake Valves.
The Corvette did have 58cc combustion chambers, similar to 305s. Iron F-body TPI 350 heads had 64cc heads.
The Corvette did have 58cc combustion chambers, similar to 305s. Iron F-body TPI 350 heads had 64cc heads.
11-03-2000, 10:19 AM
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Originally posted by Glenn91L98GTA:
305 TPI heads are not the same as Corvette (or any 350 head for that matter). All 305s got 1.84" Intake Valves. TPI 350 (Aluminum Corvette and Iron F-body) had 1.94" Intake Valves.
The Corvette did have 58cc combustion chambers, similar to 305s. Iron F-body TPI 350 heads had 64cc heads.
305 TPI heads are not the same as Corvette (or any 350 head for that matter). All 305s got 1.84" Intake Valves. TPI 350 (Aluminum Corvette and Iron F-body) had 1.94" Intake Valves.
The Corvette did have 58cc combustion chambers, similar to 305s. Iron F-body TPI 350 heads had 64cc heads.
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Godti
'89 Trans Am (Red)
305 TBI 5spd
11-03-2000, 11:30 AM
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You can use the L98 Vette heads with the 1.94" valves. You just can't fit anything bigger than that on a 305. 2.02/1.60s (common on aftermarket heads) won't clear the cylinder bores...
-Mark W.
'88 SC Camaro w/ 305 TBI
-Mark W.
'88 SC Camaro w/ 305 TBI
11-03-2000, 12:16 PM
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Car: Trans AM
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Someone told me that the L98 don't/can't use the egr stuff?? Is that true?
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Godti
'89 Trans Am (Red)
305 TBI 5spd
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Godti
'89 Trans Am (Red)
305 TBI 5spd
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11-03-2000, 01:40 PM
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What is EGR again??? and would you want to keep this on your engine?? Does EGR affect your performance??
[This message has been edited by Godti (edited November 06, 2000).]
[This message has been edited by Godti (edited November 06, 2000).]
11-06-2000, 11:49 AM
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About the manifolds and y-pipe... The TPI exhaust manifolds were different than the TBI exhaust manifolds, with the TPI manifolds have larger 2-1/4" outlets. I'm pretty sure the TPI y-pipes were a larger diameter than the TBI y-pipes to match the outlets. Plus the location of the outlets is probably slightly different between the TPI and TBI manifolds so the y-pipe could not interchange anyways.
11-07-2000, 10:49 AM
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The HO L69 305 had bigger valves, I don't know if both were bigger or just one. If you are going to swap heads onto your L03 rembmer that it has to be 87-92 and they have to be iron to fit your manifold, well you can get around that with some grinding.
------------------
1989 Pontiac Firebird Formula W6S LO3 TBI 305.
1985 Camaro IROC-Z LB9.
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1989 Pontiac Firebird Formula W6S LO3 TBI 305.
1985 Camaro IROC-Z LB9.
11-07-2000, 11:43 AM
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Originally posted by Keith5:
The HO L69 305 had bigger valves, I don't know if both were bigger or just one. If you are going to swap heads onto your L03 rembmer that it has to be 87-92 and they have to be iron to fit your manifold, well you can get around that with some grinding.
The HO L69 305 had bigger valves, I don't know if both were bigger or just one. If you are going to swap heads onto your L03 rembmer that it has to be 87-92 and they have to be iron to fit your manifold, well you can get around that with some grinding.
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Godti
'89 Trans Am (Red)
305 TBI 5spd
11-07-2000, 02:39 PM
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Car: 1986 Firebird
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EGR = Exhaust Gas Recirculation. It puts exhaust gas back into your engine to lower combustion temperatures and reduce emissions. You won't see a horsepower gain from removing it; the computer only turns it on during high-speed, low-throttle conditions when the engine's warm.
In other words, EGR comes on when you're cruising down the highway, and you're not flooring the gas pedal in a race.
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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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In other words, EGR comes on when you're cruising down the highway, and you're not flooring the gas pedal in a race.
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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!
11-08-2000, 02:02 PM
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Originally posted by Keith5:
The HO L69 305 had bigger valves, I don't know if both were bigger or just one. If you are going to swap heads onto your L03 rembmer that it has to be 87-92 and they have to be iron to fit your manifold, well you can get around that with some grinding.
The HO L69 305 had bigger valves, I don't know if both were bigger or just one. If you are going to swap heads onto your L03 rembmer that it has to be 87-92 and they have to be iron to fit your manifold, well you can get around that with some grinding.
11-08-2000, 02:50 PM
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1987+ heads have a different angle of bolts for the intake manifolds and centerbolt vavle covers. If you want to change your manifold and use parimeter valve covers, go for it.
I am not certain about the EGR with L69 heads. L69 heads are not a great flowing casting and thus not very popular. You'd be far better off with the Aluminum Corvette heads. They can easily be ported to make good flow numbers. And when you spend the money to make the L69 heads work, you could end up spending more money for less performance.
I am not certain about the EGR with L69 heads. L69 heads are not a great flowing casting and thus not very popular. You'd be far better off with the Aluminum Corvette heads. They can easily be ported to make good flow numbers. And when you spend the money to make the L69 heads work, you could end up spending more money for less performance.
11-09-2000, 10:40 AM
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Sorry I didn't check back yesterday. You can't put L69 heads on your L03. Unless they made a L69 that has a roller cam, I'm not sure if they did or didn't. Roller cam motors have center bolt valve covers. If you swap heads you will have to put heads on that were designed for a roller cam.
Do some reseach on the L69, see if the last versions had roller cams.
Do some reseach on the L69, see if the last versions had roller cams.
11-09-2000, 07:01 PM
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L69 heads have the 1.84 valves, measured mine before giving the heads away! L69 is the 83-84 HO engine, cam specs similar to L98 but non-roller since factory rollers didnt come out until 87.
11-09-2000, 11:43 PM
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Originally posted by merf23:
L69 heads have the 1.84 valves, measured mine before giving the heads away! L69 is the 83-84 HO engine, cam specs similar to L98 but non-roller since factory rollers didnt come out until 87.
L69 heads have the 1.84 valves, measured mine before giving the heads away! L69 is the 83-84 HO engine, cam specs similar to L98 but non-roller since factory rollers didnt come out until 87.
http://www.phy.duke.edu/~hartley/iroc/iroc_specs.html
I can't find the source for the bigger valves, I guess it was wrong because I looked it up on carparts.com and it says 1.84.
------------------
1989 Pontiac Firebird Formula W6S LO3 TBI 305.
1985 Camaro IROC-Z LB9.
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