C4 Why So Many With Head Work?
Drifting
Joined: Nov 2012
Posts: 1,331
Likes: 2
I disagree about the L98s intake and heads not being able to get you somewhere fast. Alot of the claims about the TPI being "Unable to feed even the 350" I think are also curious.
Here's why
Stage 2
On a 383. Obviously it's working well for that guy
obviously an aftermarket lower manifold that's ported would help things considerably. But hell, I'd say the L98 TPI intake's workin plenty good there. There's guys out there with 406s and the TPI setup.
The first vid was on a stock chip too, and I think we can agree that car probably needed a tune to really sing.
Just a question of just how fast you really want to go For me 11s would be utterly killer 
For why there are so many with headwork, if I had to guess there's quite abit of that of years on most of our cars. Mine was what 23 years old when I got it, and had 130,000. To go with the age and miles the earlier heads and gaskets had serious issues from the factory, all the research I've done told me (after purchase of the car) that replacing a headgasket even on a then New C4 wasn't an uncommon practice under warranty.
Here's why
Stage 2
On a 383. Obviously it's working well for that guy
obviously an aftermarket lower manifold that's ported would help things considerably. But hell, I'd say the L98 TPI intake's workin plenty good there. There's guys out there with 406s and the TPI setup.
The first vid was on a stock chip too, and I think we can agree that car probably needed a tune to really sing.
Just a question of just how fast you really want to go
For me 11s would be utterly killer For why there are so many with headwork, if I had to guess there's quite abit of that of years on most of our cars. Mine was what 23 years old when I got it, and had 130,000. To go with the age and miles the earlier heads and gaskets had serious issues from the factory, all the research I've done told me (after purchase of the car) that replacing a headgasket even on a then New C4 wasn't an uncommon practice under warranty.
Last edited by Aaron Keating; Dec 22, 2013 at 12:05 PM.
Burning Brakes
Joined: Jan 2000
Posts: 831
Likes: 31
From: Merritt Island Florida
Go ahead and keep LYFAO. DO you know what an "L98" is? By the time you change the heads intake system and exhaust, which is about what is required to equalize the diff between the two, you don't have a L98 anymore. You have a GM 350 short block w/a bunch of aftermarket parts on it. Not and "L98".
I do agree that both are fine motors; nothing wrong w/either.
I do agree that both are fine motors; nothing wrong w/either.
I know what an L98 is. I have owned 28 of them since 1990 and built probably 100 since then. Who said anything about changing heads?? You said changing an intake doesn't make it an L98. That is flat out wrong. TPI doesn't make the motor an L98. Come on now....that is flat out wrong and silly.
OMG I won't even retort on such a wrong post. I have an LS1 with AI LS6 heads,Fast intake etc. What motor is that now? ZZ4 is not even the same block as an L98. Look at the casting number. Changing heads/intake does not change the motor type. If I add LT4 heads/intake to an LT1 or TFS heads and convert an L98/LT1 to carb what does that make the motor???
Last edited by Mike 92LX; Dec 22, 2013 at 12:22 PM.
Burning Brakes
Joined: Jan 2000
Posts: 831
Likes: 31
From: Merritt Island Florida
I disagree about the L98s intake and heads not being able to get you somewhere fast. Alot of the claims about the TPI being "Unable to feed even the 350" I think are also curious.
Here's why
Hole-Shot's C4 Corvette, 383 Stroker TPI. Mods=Stage 1 - YouTube
Stage 2
Hole-Shot's C4 Corvette, 383 Stroker TPI. Mods=Stage 2. Vigilante Torque Convertor - YouTube
On a 383. Obviously it's working well for that guy
obviously an aftermarket lower manifold that's ported would help things considerably. But hell, I'd say the L98 TPI intake's workin plenty good there. There's guys out there with 406s and the TPI setup.
The first vid was on a stock chip too, and I think we can agree that car probably needed a tune to really sing.
Just a question of just how fast you really want to go For me 11s would be utterly killer
For why there are so many with headwork, if I had to guess there's quite abit of that of years on most of our cars. Mine was what 23 years old when I got it, and had 130,000. To go with the age and miles the earlier heads and gaskets had serious issues from the factory, all the research I've done told me (after purchase of the car) that replacing a headgasket even on a then New C4 wasn't an uncommon practice under warranty.
Here's why
Hole-Shot's C4 Corvette, 383 Stroker TPI. Mods=Stage 1 - YouTube
Stage 2
Hole-Shot's C4 Corvette, 383 Stroker TPI. Mods=Stage 2. Vigilante Torque Convertor - YouTube
On a 383. Obviously it's working well for that guy
obviously an aftermarket lower manifold that's ported would help things considerably. But hell, I'd say the L98 TPI intake's workin plenty good there. There's guys out there with 406s and the TPI setup.
The first vid was on a stock chip too, and I think we can agree that car probably needed a tune to really sing.
Just a question of just how fast you really want to go
For me 11s would be utterly killer For why there are so many with headwork, if I had to guess there's quite abit of that of years on most of our cars. Mine was what 23 years old when I got it, and had 130,000. To go with the age and miles the earlier heads and gaskets had serious issues from the factory, all the research I've done told me (after purchase of the car) that replacing a headgasket even on a then New C4 wasn't an uncommon practice under warranty.
BINGO.
The stock prom is not as bad as people say with the stock cam either but the cars do run very rich due to emissions. Tell you guys what. I will look for an L98 car after the holidays. I will even get a convertable with tall gears with an automatic wityh some 100-130K on it-a good average car. I need a car like that at my Florida home anyway. I will show how easy it is to run low 14s and even high 13s without going into the motor on that heavy car at stock weight with stock wheels,gears etc. Plug choice,gap,shift points,cable adjustment and tune up is really important. The stock injectors are trash as is the stock fuel pressure,stock wires,stock coil and timing(which you can't adjust on an LT1). You can make a fun car on a budget or as a first timer.
Le Mans Master
Joined: Oct 2008
Posts: 9,758
Likes: 49
From: Houston Texas
Sorry Mike, the L98 is just a SBC I dont care what you say or how silly you think my post is. The fact is once you pull the intake off the L98 regardless of casting #s its just a SBC.
I have a LM7 bored over to 5.7 with forged internals 241 heads and a LS6 intake in my C4. That is refereed to as an LSx and I imagine your would be too.
Aaron we are referring to the "stock TPI" Holeshot's vette is not stock TPI. The stock LTR set up sux.
I have a LM7 bored over to 5.7 with forged internals 241 heads and a LS6 intake in my C4. That is refereed to as an LSx and I imagine your would be too.
Aaron we are referring to the "stock TPI" Holeshot's vette is not stock TPI. The stock LTR set up sux.
Last edited by ch@0s; Dec 22, 2013 at 03:46 PM.
Drifting
Joined: Nov 2012
Posts: 1,331
Likes: 2
Sorry Mike, the L98 is just a SBC I dont care what you say or how silly you think my post is. The fact is once you pull the intake off the L98 regardless of casting #s its just a SBC.
I have a LM7 bored over to 5.7 with forged internals 241 heads and a LS6 intake in my C4. That is refereed to as an LSx and I imagine your would be too.
Aaron we are referring to the "stock TPI" Holeshot's vette is not stock TPI. The stock LTR set up sux.
I have a LM7 bored over to 5.7 with forged internals 241 heads and a LS6 intake in my C4. That is refereed to as an LSx and I imagine your would be too.
Aaron we are referring to the "stock TPI" Holeshot's vette is not stock TPI. The stock LTR set up sux.
I can't help but wonder what holeshot's vette would have done with the aftermarket base manifolds, and a tune myself.
Drifting
Joined: Nov 2012
Posts: 1,331
Likes: 2
How much better though? (note I already have the edlebrock lower manifold. Why port something that won't flow as good as an aftermarket unit out of the box?)
For that matter what would he have done with a 400, or even a 406 in there
(guess who came into a good 400 block...for free)
For that matter what would he have done with a 400, or even a 406 in there
(guess who came into a good 400 block...for free)
Last edited by Aaron Keating; Dec 22, 2013 at 05:16 PM.
Le Mans Master
Joined: Oct 2008
Posts: 9,758
Likes: 49
From: Houston Texas
How much better though? (note I already have the edlebrock lower manifold. Why port something that won't flow as good as an aftermarket unit out of the box?)
For that matter what would he have done with a 400, or even a 406 in there
(guess who came into a good 400 block...for free)
For that matter what would he have done with a 400, or even a 406 in there
(guess who came into a good 400 block...for free)
Here is a good read/comparison. http://xtremecarzone.com.au/index.php?showtopic=386
PDF version for download..http://xtremecarzone.com.au/STORAGE/...akeOptions.pdf
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Michael S. Palmer
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
I don't think that you do. You may have had 28 of them, but apparently, you need more, to figure it out.
"Silly"...Good one. "Flat out wrong". An L98 is an RPO code for a very specific combination of parts that make an engine. Saying that changing the top end of the motor and it's still that same combination of part...THAT is flat out WRONG. And....a little "silly" too. 
Not an LS1, and not an LT1, and NOT and L98. Changing heads and cam absolutely DOES change the motor type. You betcha! 
I have an LS1 with AI LS6 heads,Fast intake etc. What motor is that now? ZZ4 is not even the same block as an L98. Look at the casting number. Changing heads/intake does not change the motor type. If I add LT4 heads/intake to an LT1 or TFS heads and convert an L98/LT1 to carb what does that make the motor???
Last edited by Tom400CFI; Dec 22, 2013 at 10:18 PM.
Burning Brakes
Joined: Jan 2000
Posts: 831
Likes: 31
From: Merritt Island Florida
LMAO!! Whatever you say. An L98 is is an L98 no matter what induction is on it. RPO code is an L98??????????????????????????????????LMA O!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!
So what is my LS1 now with LS6 heads and a fast intake? It is no longer an LS1???
What is an L98 with a miniram and tfs heads on it called? Its no longer an L98 since it doesn't have factory TPI on it????
I just built an LT1 with LT4 heads and intake and another with TFS heads and converted to carb. What are they now? Not an LT1?
I never said an L98 is not a SBC. Saying a new GM crate motor is the same as L98 is just flat out wrong. It is not by a long shot.
My goodness.....I am out of this thread before I laugh more and my head starts to hurt
So what is my LS1 now with LS6 heads and a fast intake? It is no longer an LS1???
What is an L98 with a miniram and tfs heads on it called? Its no longer an L98 since it doesn't have factory TPI on it????
I just built an LT1 with LT4 heads and intake and another with TFS heads and converted to carb. What are they now? Not an LT1?
I never said an L98 is not a SBC. Saying a new GM crate motor is the same as L98 is just flat out wrong. It is not by a long shot.
My goodness.....I am out of this thread before I laugh more and my head starts to hurt
Race Director
Joined: May 2006
Posts: 10,691
Likes: 71
From: Phoenix Arizona
LMAO!! Whatever you say. An L98 is is an L98 no matter what induction is on it. RPO code is an L98??????????????????????????????????LMA O!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!
So what is my LS1 now with LS6 heads and a fast intake? It is no longer an LS1???
What is an L98 with a miniram and tfs heads on it called? Its no longer an L98 since it doesn't have factory TPI on it????
I just built an LT1 with LT4 heads and intake and another with TFS heads and converted to carb. What are they now? Not an LT1?
I never said an L98 is not a SBC. Saying a new GM crate motor is the same as L98 is just flat out wrong. It is not by a long shot.
My goodness.....I am out of this thread before I laugh more and my head starts to hurt
So what is my LS1 now with LS6 heads and a fast intake? It is no longer an LS1???
What is an L98 with a miniram and tfs heads on it called? Its no longer an L98 since it doesn't have factory TPI on it????
I just built an LT1 with LT4 heads and intake and another with TFS heads and converted to carb. What are they now? Not an LT1?
I never said an L98 is not a SBC. Saying a new GM crate motor is the same as L98 is just flat out wrong. It is not by a long shot.
My goodness.....I am out of this thread before I laugh more and my head starts to hurt
Max G’s
Joined: Nov 2008
Posts: 2,751
Likes: 79
From: Monroe OH
NCM Sinkhole Donor
OMG here we go again L98 vs LT1. 
GrandeDave- the L98 is a good dependable engine. As fore mentioned the head gaskets usually just need replaced in the higher mile car due to different exapansion rates between the AL head and Iron Block. No big deal. The L98 is easy and less expensive to repair in my experience.
GrandeDave- the L98 is a good dependable engine. As fore mentioned the head gaskets usually just need replaced in the higher mile car due to different exapansion rates between the AL head and Iron Block. No big deal. The L98 is easy and less expensive to repair in my experience.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
LT engines start out with a head-start with: HP intake, more compression, reverse cooling, better exhaust, and better flowing heads. To improve the LTx platform for more power COULD require less money.
OTOH, for people doing complete builds, the difference isn't as stark. If you swap intakes, headers, cam, exhaust, heads, and stroke it (for both platforms), the "power potential" probably isn't much different. If so, it would come down to the reverse cooling design [providing a big more anti-knock protection].
Really power train issues can also be similar - in cost/challenge.
Personally, I'd say the LT motors have easier power -- as Cliff said.
From my perspective, the issue on power potential is a wide-open comment. Do you include turbos, superchargers, and any other possible POTENTIAL modification? What's the limit -- when you say potential?
Le Mans Master
Joined: Oct 2008
Posts: 9,758
Likes: 49
From: Houston Texas
Oh yeah, What were we talking about?
I chose the 91 because I planned on modding. I like the late look and the support of the SBC. Not to say you cant mod a LT1 but that was my choice. I guess I don't have to worry about that now.
I chose the 91 because I planned on modding. I like the late look and the support of the SBC. Not to say you cant mod a LT1 but that was my choice. I guess I don't have to worry about that now.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Make sure you let this guy know he doesn't need an intake (or TB)...
http://forums.corvetteforum.com/c4-t...4-upgrade.html
(I'm not going to tell him because I don't know what you can get out of a stock LT1 intake. Seen too many convert to the LT4 Edelbrock piece.
Drifting
Joined: Dec 2011
Posts: 1,439
Likes: 23
From: mesa az
GM's explanation for 113 failures (and there were many - it's how I found this place over 10 years ago) was mis-positioned intake gaskets that resulted in leaks that resulted in galvanic corrosion that ate up the gasket. Almost always at #7 and a great many near the end of the original 3/36 warranty which some Dealers denied. A few brave souls then sued GM and they redesigned the 113 with counterbores at the front and rear intake gasket mounts. Those bores accepted gaskets fitted with retainers which then maintained perfect alignment of the gasket during assembly. Only the '91 received that modification, but it's on the ZZ4 (which uses 113 heads) and current production 113's from GM Performance Parts. The good news is that it did occur at fairly low miles with complete failure at around 50,000. The bad news is that the acidic mix weeping into the cylinder often wore a groove into the deck of the block meaning a correct repair required a new block which not everyone did or does and you're forever replacing head gaskets. Clues are yucky looking coolant within months of a coolant change, plugged up heater cores, excessive coolant temps and a Block Learn showing a Lean burn. Compression on motors with a weeping gasket is usually normal. Check for a plug that's cleaner than the rest and for rust on the threads or do a leakdown test - particularly if you're purchasing a low mileage example.
