Upgrades for C4?
Discussion
Hi, I am new to the idea of corvette ownership, so any help welcomed? I went to look at a nice standard black manual C4 convertible today, was told to expect about 300 hp as standard. Are there any common performance upgrades for these? Or if i want more power, should i just buy a newer car?
Thanks, Dean
Thanks, Dean
Edited for muppetery by deeen on Thursday 21st January 19:05
Edited by deeen on Thursday 21st January 19:06
Or 375-405 Hp out of a ZR-1
Just for a bit of a help, early cars (86-91) used the first gen engine, which apart from the unique 1984 engine (205 Hp, cross fire injection) are L98 'Tuned Port Injection' - these were rated from 230hp to 250 Hp dependent on year.
1992 saw the introduction of the LT1 - that's the 300 Hp motor, you could also get the LT4 which was a tuned version of the LT1, which is 330Hp. This engine is a better breathing engine, although it is a lot more revvy and has a less torquey character than the L98's. These are referred to as 'second gen' engines, and give a better initial point to start tuning from, but be aware that more parts are available for tuning first gen engines.
The LT5 - the ZR1 motor (first time round) was available 1990 to 1994 - this was a special developed by GM and Lotus, shares not much at all really with any other small blocks, is a quad cam four valve monster, starts at 375-405 from the factory, although some like Cliff's and Gixers are over 500 HP now.
Tuning wise, well sky's the limit and depends on your pocket. There's a couple of guys on CCCUK (Dan T and Adi4) that tuned L98's to take the recent informal drag racing series they had (Dan's was definitely an L98 based, Adi's may be an LT1) - they were into the 12.5's from memory. They've used remapped engines, heads, cam, and the unrestrictive LT1 intake in a conversion they have developed. Basically a good NA tune.
Other alternatives are supercharging (some co's offer turbo, but these seem less proven) - such as Vortech and Procharger, or even a whacking great Rootes unit through the bonnet vintage drag racer style.
What year of convertible was it? One thing the convertibles do get saddled with is a taller final drive ratio - it was to make them a bit more refined, this can blunt the go a little.
Hope this helps!
Francis.
Just for a bit of a help, early cars (86-91) used the first gen engine, which apart from the unique 1984 engine (205 Hp, cross fire injection) are L98 'Tuned Port Injection' - these were rated from 230hp to 250 Hp dependent on year.
1992 saw the introduction of the LT1 - that's the 300 Hp motor, you could also get the LT4 which was a tuned version of the LT1, which is 330Hp. This engine is a better breathing engine, although it is a lot more revvy and has a less torquey character than the L98's. These are referred to as 'second gen' engines, and give a better initial point to start tuning from, but be aware that more parts are available for tuning first gen engines.
The LT5 - the ZR1 motor (first time round) was available 1990 to 1994 - this was a special developed by GM and Lotus, shares not much at all really with any other small blocks, is a quad cam four valve monster, starts at 375-405 from the factory, although some like Cliff's and Gixers are over 500 HP now.
Tuning wise, well sky's the limit and depends on your pocket. There's a couple of guys on CCCUK (Dan T and Adi4) that tuned L98's to take the recent informal drag racing series they had (Dan's was definitely an L98 based, Adi's may be an LT1) - they were into the 12.5's from memory. They've used remapped engines, heads, cam, and the unrestrictive LT1 intake in a conversion they have developed. Basically a good NA tune.
Other alternatives are supercharging (some co's offer turbo, but these seem less proven) - such as Vortech and Procharger, or even a whacking great Rootes unit through the bonnet vintage drag racer style.
What year of convertible was it? One thing the convertibles do get saddled with is a taller final drive ratio - it was to make them a bit more refined, this can blunt the go a little.
Hope this helps!
Francis.
Deeen what year C4 have you got, is it manual or auto and has it had any mods thus far??
I've been running a '94 C4 for a number of years and compete in a number of drag race series's so happy to offer advice once I know the basics of what you've got and what you hope to achieve with the car.
I've been running a '94 C4 for a number of years and compete in a number of drag race series's so happy to offer advice once I know the basics of what you've got and what you hope to achieve with the car.
franv8 said:
Tuning wise, well sky's the limit and depends on your pocket. There's a couple of guys on CCCUK (Dan T and Adi4) that tuned L98's to take the recent informal drag racing series they had (Dan's was definitely an L98 based, Adi's may be an LT1) - they were into the 12.5's from memory. They've used remapped engines, heads, cam, and the unrestrictive LT1 intake in a conversion they have developed. Basically a good NA tune.
http://www.youtube.com/watch?v=XnLis77oQp0Edited by the-esses on Saturday 23 January 22:56
Nice videos, thanks the-esses! Jakester i don't have one yet, i'm looking for a change of car, and i went to see a late C4 manual convertible, the black one at claremont corvette. Totally standard, 300hp I was told. I want to achieve it feeling faster than my old Chim, 300hp (up from 267 std) and 1200kg. Weekend road use plus occcasional track day.
FranV8 thanks for the detailed post, just what i needed to start my education in these cars! The LT5 sounds great... 375-400hp? Mmmm... Any less reliable? And they all seem a bit thin on the ground, for now...
Mind you, i think searching for a manual convertible, i am limiting my own choice... I have registered on direct auto export, i'm wodering how the cost of importing adds up? Are USA hp different from UK hp?
Just noticed a C5 advertised for exactly the same price as the C4 I went to see. Advertised at 345hp standard? Is the C4 more desireable for some reason? Or should i just start with the newest one i can afford?
As you can tell, i am very much at the start of this process... all help welcomed, thanks Dean
FranV8 thanks for the detailed post, just what i needed to start my education in these cars! The LT5 sounds great... 375-400hp? Mmmm... Any less reliable? And they all seem a bit thin on the ground, for now...
Mind you, i think searching for a manual convertible, i am limiting my own choice... I have registered on direct auto export, i'm wodering how the cost of importing adds up? Are USA hp different from UK hp?
Just noticed a C5 advertised for exactly the same price as the C4 I went to see. Advertised at 345hp standard? Is the C4 more desireable for some reason? Or should i just start with the newest one i can afford?
As you can tell, i am very much at the start of this process... all help welcomed, thanks Dean
deeen said:
Just noticed a C5 advertised for exactly the same price as the C4 I went to see. Advertised at 345hp standard? Is the C4 more desireable for some reason? Or should i just start with the newest one i can afford?
As you can tell, i am very much at the start of this process... all help welcomed, thanks Dean
C5 has a number of advantages. For verts, the C5 has an opening boot/trunk - C4 doesn't. C5 chassis is much more rigid which has the obvious benefits plus it's reckoned to make the C5s a lot more water-tight than C4s. The LS1 engine in the C5 has more power out of the box at 344-350hp depending on the year. You can also get the HUD on the C5 which is the best thing since sliced bread.As you can tell, i am very much at the start of this process... all help welcomed, thanks Dean
You should find a standard C5 feels a little quicker than a standard Chimera 4.0 out of the box. The C5 weighs a little under 1.5 tonnes, so it's what you expect given the power-to-weight.
You need to go and drive a C4 & a C5 you'll soon decide from there, both models have +/-'s but it'll come down to budget & personal choice.
Definately try a manual C5 as I find them more fun than the autos, as for money £7-8k will find a good clean C4, £12k will find a C5.
As for bhp, my LT1 C4 (heavily modded) puts out 550bhp so big numbers are obtainable..
Definately try a manual C5 as I find them more fun than the autos, as for money £7-8k will find a good clean C4, £12k will find a C5.
As for bhp, my LT1 C4 (heavily modded) puts out 550bhp so big numbers are obtainable..
One of these could make a C4 accelerate that little bit quicker 
http://cgi.ebay.co.uk/Chevrolet-Corvette-Diff-Unit...
http://cgi.ebay.co.uk/Chevrolet-Corvette-Diff-Unit...
deeen said:
Nice videos, thanks the-esses! Jakester i don't have one yet, i'm looking for a change of car, and i went to see a late C4 manual convertible, the black one at claremont corvette. Totally standard, 300hp I was told. I want to achieve it feeling faster than my old Chim, 300hp (up from 267 std) and 1200kg. Weekend road use plus occcasional track day.
FranV8 thanks for the detailed post, just what i needed to start my education in these cars! The LT5 sounds great... 375-400hp? Mmmm... Any less reliable? And they all seem a bit thin on the ground, for now...
Mind you, i think searching for a manual convertible, i am limiting my own choice... I have registered on direct auto export, i'm wodering how the cost of importing adds up? Are USA hp different from UK hp?
Just noticed a C5 advertised for exactly the same price as the C4 I went to see. Advertised at 345hp standard? Is the C4 more desireable for some reason? Or should i just start with the newest one i can afford?
As you can tell, i am very much at the start of this process... all help welcomed, thanks Dean
As others have said, sky's the limit.FranV8 thanks for the detailed post, just what i needed to start my education in these cars! The LT5 sounds great... 375-400hp? Mmmm... Any less reliable? And they all seem a bit thin on the ground, for now...
Mind you, i think searching for a manual convertible, i am limiting my own choice... I have registered on direct auto export, i'm wodering how the cost of importing adds up? Are USA hp different from UK hp?
Just noticed a C5 advertised for exactly the same price as the C4 I went to see. Advertised at 345hp standard? Is the C4 more desireable for some reason? Or should i just start with the newest one i can afford?
As you can tell, i am very much at the start of this process... all help welcomed, thanks Dean
Latter C4's with the LT1 5.7 litre V8 are very tunable and not too silly price wise to do.
Lots of options from n/a, to bigger displacement (383ci+), to nitrous oxide or supercharger kits.
No reason the LT1 can't be made to produce 400-500hp with the right parts.
The older L98 is still a good engine, but it'll be more expensive and difficult to get as much hp from it.
The LT5 is a bit of an oddball beast. Sure on paper it sounds good and in reality it is too. But its a far more complex engine. So expect tuning to be more specialised and expensive. I personally love the look of the ZR-1 and its whole existence, but there is no denying that it can be cheaper to simply tune the LT1 to out perform it.
A C5 Corvette is quite a different beast to a C4. In terms of looks, the C5 always looks better in person than in pics, but some don't like the large rear.
Personally I love both, although I do think the C4 has some superb lines and has aged very well. That said, C4 prices have slumped at present, so they make a very good value buy (so long as you don't overpay) and they are unlikely to lose much value.
The C5 uses the much newer aluminium LS1 5.7 V8. This engine is the reason the fancy LT5 from the ZR-1 was discontinued. The LS1 is smaller, shorter (height and length), lighter and makes very similar HP.
Factory rated at 345hp. But can easily be made to make a lot more power. The LS6 variant found in the C5 z06 made 405hp from 5.7 litres while still retaining the OHV configuration compared to similar HP from the Quad cam DOHC LT5 in the ZR-1.
If its performance you want then a C5 will be a better platform to build from. Very capable in stock trim with loads of potential.
A C4 is still a fast machine, but you have to remember it was originally conceived in the late 70's/early 80's. Things like ride quality won't be as good.
But it all depends on price and future plans.
A ZR-1 will always be more sort after, so likely to fetch more money in time to come, but you'll pay more to get one.
C5's will probably continue to drop in price a bit until they reach the same level as C4's are currently.
If you want to learn more your best bet is to join one of the US based Corvette forums
The C5 is a much better built car than the C4. The C4 Corvette feels fast and even with my 1985 235hp TPi (with a chip adding maybe 15hp), very little could touch its response and torque low down and it would run up to 150 without too much fuss. It was enormous fun to drive too. Early digital instrument panels can go wrong, they can get dog-eared inside too and as stated, C4s do tend to leak.
They face-lifted the C4 in 1991 to a curved look from the lantern-jawed look but only in 92 did it get the LT1 along with the 6 speed box. The LT1 gets a mixed press as has Optispark ignition - a large plate-like device on the crank right in the firing line of water. All C4s have iron block engines. There was an LT4 330hp engine in the 1996 GS.
For me, if you can get a C5, even though I love C4s, it's a no-brainer. I had a Z06 (which had the HUD, the stock ones didn't)and it was so much more capable, much better built and so much more together as an overall design that it was a quantum leap. It also had the fantastic all-alloy LS1 with 8 individual coils, much easier to look after and more reliable. It also uses 18" wheels where the C4s use 16 and 17s so tyre hoice is more limited.
The Corvette gearbox is not the last word in smoothness or dexterity so don't rule out the auto prematurely.
It's a hard one for me as I thought the C4s lower limits and character made it more fun than the Z06 but the Z06 was crushingly more capable with much higher limits. It also has better balance with a rear-mounted transaxle. The C4 is standard front engine, front gearbox.
Whatever you choose, I doubt you'll be disappointed in any way. Check for damage to sills and floor though as some idiots tend to try to jack them up on the fibreglass and the floor of the C5 is pretty sophisticated.
They face-lifted the C4 in 1991 to a curved look from the lantern-jawed look but only in 92 did it get the LT1 along with the 6 speed box. The LT1 gets a mixed press as has Optispark ignition - a large plate-like device on the crank right in the firing line of water. All C4s have iron block engines. There was an LT4 330hp engine in the 1996 GS.
For me, if you can get a C5, even though I love C4s, it's a no-brainer. I had a Z06 (which had the HUD, the stock ones didn't)and it was so much more capable, much better built and so much more together as an overall design that it was a quantum leap. It also had the fantastic all-alloy LS1 with 8 individual coils, much easier to look after and more reliable. It also uses 18" wheels where the C4s use 16 and 17s so tyre hoice is more limited.
The Corvette gearbox is not the last word in smoothness or dexterity so don't rule out the auto prematurely.
It's a hard one for me as I thought the C4s lower limits and character made it more fun than the Z06 but the Z06 was crushingly more capable with much higher limits. It also has better balance with a rear-mounted transaxle. The C4 is standard front engine, front gearbox.
Whatever you choose, I doubt you'll be disappointed in any way. Check for damage to sills and floor though as some idiots tend to try to jack them up on the fibreglass and the floor of the C5 is pretty sophisticated.
franv8 said:
vetteheadracer said:
Loved both C4 and C5, C5 much better track day car as it has brakes. C5 also easier to work on compared with a C4 and easier to get bigger horsepower.
Brakes are for girls.vetteheadracer said:
franv8 said:
vetteheadracer said:
Loved both C4 and C5, C5 much better track day car as it has brakes. C5 also easier to work on compared with a C4 and easier to get bigger horsepower.
Brakes are for girls.No, brakes are for faster lap times
I concur! C5 for the win. Primarily for the LS engine. The only caveat is that the early 98 model ECU was a one off all the other models use the 99+ ECU. So the 98 is best avoided as there are tuning limitations in it. Especially if you want to modify.
Converting from a 98 to 99 ECU in he US is a common first step when modding for more power.
You will find all the cheap C5's are the 98MY all the 99+ ones come at a premium of about £3k+ not sure why, I wouldnt have thought it was because of the ECU issue, but you never know.
The LS engine is available in displacements of up to 500 cubes (tall deck block) An LS engine came a very close second in the Jegs Engine masters challenge this year. SAM racing has an NA 431 cube engine running 1000bhp. They are the latest and greatest engine for performance and there are tons of mods around for them.
It was also voted best engine by Ward's one year and won most fuel efficient engine for the Corvette team a couple of years back.
In other words, you have no option but to buy a C5
Personally Im on the lookout for a C6 as I like the styling more than the C5, plus they have the new GenIV LS engine rather than the older Gen3 model of the C5's. What you really want is a C6 Z06 though. But they are a little costly, but excellent value for money!
Converting from a 98 to 99 ECU in he US is a common first step when modding for more power.
You will find all the cheap C5's are the 98MY all the 99+ ones come at a premium of about £3k+ not sure why, I wouldnt have thought it was because of the ECU issue, but you never know.
The LS engine is available in displacements of up to 500 cubes (tall deck block) An LS engine came a very close second in the Jegs Engine masters challenge this year. SAM racing has an NA 431 cube engine running 1000bhp. They are the latest and greatest engine for performance and there are tons of mods around for them.
It was also voted best engine by Ward's one year and won most fuel efficient engine for the Corvette team a couple of years back.
In other words, you have no option but to buy a C5
Personally Im on the lookout for a C6 as I like the styling more than the C5, plus they have the new GenIV LS engine rather than the older Gen3 model of the C5's. What you really want is a C6 Z06 though. But they are a little costly, but excellent value for money!
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