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Hello, I've recently acquired a 1995 LT1 auto with 84k original miles. No mods that I can tell; maybe final gear ratio is different from stock but I'm speculating.
Interior is ok, certainly could use some love and exterior is great. Sway bar link is getting replaced presently, and I'll likely replace ball joints and tie rod ends soon.
Engine seemed totally fine upon purchase about 3 weeks ago but has recently developed an oil leak. I need to track that down and evaluate.
My end goal is to keep it original like a new '95 vette, but enough power to run low 12's in the quarter. I've narrowed this down to either build the LT1 and add forced induction, or crate motor with aftermarket ECM. I'm interested in opinions from those with experience with either of these projects.
I was a diesel mechanic in the military back in the 90's, have since moved on to other things but can take on mechanical diy with exception to engine building.
Once you track down the oil leak - I'd suggest changing all fluids (engine oil, brake fluid, trans fluid, coolant, diff oil and P.S. fluid. Throw on a new fuel filter for good measure while you're at it.
So - you want to run in the 12's - first question - are you willing to use sticky drag rubber to do so - or do you want to do it with street tires ??? Second question - do you want to keep your stock rear end gear ratio or are you willing to go with something a bit numerically higher and lose some highway mileage ??
If the answer to both is yes - a set of long tube headers, a "moderate" cam and a better set of heads (and of course the requisite tune to go with those mods) will probably get you there.
I will warn you that the Dana 36 rear end that comes in the auto cars is somewhat less "tolerant" of abuse than the Dana 44 in the stick cars, and when you start to run sticky tires - you start to put the rear end at risk.... Limit the "shock loading" that you apply to the rear end, and it'll probably be alright for quite a while - do things like a trans brake and your rear end life may be measured in fractions of a night at the strip.
Once you track down the oil leak - I'd suggest changing all fluids (engine oil, brake fluid, trans fluid, coolant, diff oil and P.S. fluid. Throw on a new fuel filter for good measure while you're at it.
So - you want to run in the 12's - first question - are you willing to use sticky drag rubber to do so - or do you want to do it with street tires ??? Second question - do you want to keep your stock rear end gear ratio or are you willing to go with something a bit numerically higher and lose some highway mileage ??
If the answer to both is yes - a set of long tube headers, a "moderate" cam and a better set of heads (and of course the requisite tune to go with those mods) will probably get you there.
I will warn you that the Dana 36 rear end that comes in the auto cars is somewhat less "tolerant" of abuse than the Dana 44 in the stick cars, and when you start to run sticky tires - you start to put the rear end at risk.... Limit the "shock loading" that you apply to the rear end, and it'll probably be alright for quite a while - do things like a trans brake and your rear end life may be measured in fractions of a night at the strip.
My stated goal is to have enough power to run 12's in the quarter, but it's primarily going to be a street car. If It were going to be mostly strip then I would start with increasing traction, reducing weight, stall converter, shift kit etc.
Maybe I should just re-word the goal to be a hp target; but I'm not sure what that is for the c4. My previous car was a 911turbo with 450awhp and weighed about 3500lbs. Since it relied on heavy boost the power curve was dramatic after 3000rpm. I would assume the LT1 wouldn't actually need a peak hp as high since the area under the curve is distributed more evenly.
I guess i'm looking for pros and cons on specifically the engine projects I mentioned. Supercharge the LT1 vs a n/a crate motor with a dyno-proven output, for a street car.
One of the biggest attributes of the LT1 is 300 Ft LB of torque from about 1,800 RPM thru 5,500+ RPM. You don't have to drop two gears to pass someone on the highway - just squeeze the throttle, and you're done. On the track - HP wins - but it's because the drivers keep the engine in the sweet spot of the power band ALL THE TIME, but the street - torque is king.
SO - back to your LT1 - a decent benchmark for a NA engine is 1.2 - 1.25 Hp/cubic inch. Sure you can get more than that - but to go much higher typically involves mods that make the engine marginally streetable (big duration cams, heads with Big intake ports, etc. etc. etc.) - and you lose that wonderful low end torque... So - with a 350- you're talking about low 400's in HP while maintaining decent "streetability". A common practice is to use a longer stroke crank on the 350 - with a 0.030 overbore - which turns the engine into a 383 - so at that point mid 400 HP numbers are attainable.
I should have mentioned this in my original reply - but typically LT1 Vettes are high 13sec cars from the factory. Generally speaking - to go 0.1 sec faster in the quarter requires 10 HP in a 3,000 Lb car. So - you're talking about adding 150 HP to get into the low - mid 12's on motor alone.
When you're talking 450 HP - you're talking about a 50% power increase over the factory level - and remember the LT1 was a "hot" factory engine in the day. At that power level, the stock hypereutectic pistons are pretty marginal, as are the factory rod bolts, so most people who are at that power level have done significant work to the rotating assembly. Heavy porting or good aftermarket heads are normal at that power level, and the cam is typically starting to get pretty lumpy... The LT1 block is a pretty decent piece - but it's nowhere near as strong as an aftermarket Gen I Small block casting.
If you want much more than that - you're probably going to need even more displacement or forced induction. There aren't many Blower or Turbo set-ups for the LT1/LT4 engines. some exist - but not a lot of choices. When you deal with Forced Induction you typically want to intercool to try to cut down the intake temp, and you need significant fuel supply improvements. Lots and lots of $$$ can easily start flowing.
Spend some time searching through this forum - see what others are running, and think about a 400 ish HP LT1 small block with decent heads ($1,5000), long tube headers ($900 or so) and maybe a small cam ($400 for a kit - but a lot of time to install), and a tune ($500 and up)... . The old GM LT4 "Hot Cam Kit" was able to make 425 HP or so and that was similar to what I'm talking about (that GM Hot Cam is slightly hotter than I'd recommend for a street car with an automatic and a stock converter, but the LT4 heads while good - are not as good as some of the aftermarket alternatives that are out there).
So for $3,500 or so in parts - you're probably in the high 12's / low 13's . Just my opinion - but - Not a bad place to be....
One of the biggest attributes of the LT1 is 300 Ft LB of torque from about 1,800 RPM thru 5,500+ RPM. You don't have to drop two gears to pass someone on the highway - just squeeze the throttle, and you're done. On the track - HP wins - but it's because the drivers keep the engine in the sweet spot of the power band ALL THE TIME, but the street - torque is king.
SO - back to your LT1 - a decent benchmark for a NA engine is 1.2 - 1.25 Hp/cubic inch. Sure you can get more than that - but to go much higher typically involves mods that make the engine marginally streetable (big duration cams, heads with Big intake ports, etc. etc. etc.) - and you lose that wonderful low end torque... So - with a 350- you're talking about low 400's in HP while maintaining decent "streetability". A common practice is to use a longer stroke crank on the 350 - with a 0.030 overbore - which turns the engine into a 383 - so at that point mid 400 HP numbers are attainable.
I should have mentioned this in my original reply - but typically LT1 Vettes are high 13sec cars from the factory. Generally speaking - to go 0.1 sec faster in the quarter requires 10 HP in a 3,000 Lb car. So - you're talking about adding 150 HP to get into the low - mid 12's on motor alone.
When you're talking 450 HP - you're talking about a 50% power increase over the factory level - and remember the LT1 was a "hot" factory engine in the day. At that power level, the stock hypereutectic pistons are pretty marginal, as are the factory rod bolts, so most people who are at that power level have done significant work to the rotating assembly. Heavy porting or good aftermarket heads are normal at that power level, and the cam is typically starting to get pretty lumpy... The LT1 block is a pretty decent piece - but it's nowhere near as strong as an aftermarket Gen I Small block casting.
If you want much more than that - you're probably going to need even more displacement or forced induction. There aren't many Blower or Turbo set-ups for the LT1/LT4 engines. some exist - but not a lot of choices. When you deal with Forced Induction you typically want to intercool to try to cut down the intake temp, and you need significant fuel supply improvements. Lots and lots of $$$ can easily start flowing.
Spend some time searching through this forum - see what others are running, and think about a 400 ish HP LT1 small block with decent heads ($1,5000), long tube headers ($900 or so) and maybe a small cam ($400 for a kit - but a lot of time to install), and a tune ($500 and up)... . The old GM LT4 "Hot Cam Kit" was able to make 425 HP or so and that was similar to what I'm talking about (that GM Hot Cam is slightly hotter than I'd recommend for a street car with an automatic and a stock converter, but the LT4 heads while good - are not as good as some of the aftermarket alternatives that are out there).
So for $3,500 or so in parts - you're probably in the high 12's / low 13's . Just my opinion - but - Not a bad place to be....
Thank you for that. Lots of good info! Reading this forum and watching youtube for as much LT1 related material I can get. It's a shame many of the links I find are no longer active but I guess that's to be expected for an aging platform.
Have you ever pulled your engine? If replacing heads I think I would be compelled to get new rings and crank/rod bearings in there as well. Complexity goes way up for stroker rotating assembly so I wouldn't want to diy that one. Not great at machining.
Have you ever pulled your engine? If replacing heads I think I would be compelled to get new rings and crank/rod bearings in there as well. Complexity goes way up for stroker rotating assembly so I wouldn't want to diy that one. Not great at machining.
YEP - I've pulled engines out of a couple of C4's. It's not terribly fun - but it's not impossible either. I have never pulled a motor out of auto car - only the 6 speed cars - on those - I pulled the tranny first - then pulled the motor out. I go in with the engine hoist perpendicular to the centerline of the car (aka - from the side). You can get the heads off in a day or so - about another day to put things back together again. The only really annoying part about the head removal is that there is a tube in the back of the motor (it's a "steam tube" that is connected to each head with a "banjo bolt" - those "banjo bolts" are not fun to get to.
You can check out "Golen Engine Service" in NH - Chad Golen does a lot of work on LT1 motors and knows his way around them pretty well. You could just buy a stroked Short block from him, or send him your short block for building... You typically have to do a bit of "clearancing" of the lower cylinder bore to allow for rod bolt clearance with the stroker crank - and if you get too aggressive - or grind in the wrong place you'll find the water jacket - so that job is best left to someone who has some experience.
If the car has been taken care of - you may well have lots of life left in the rings and bearings - you can tell a lot about the maintenance habits of the prior owner(s) by pulling a valve cover and looking at how "clean" things are. If there is baked on sludge on stuff (the valve cover itself, rocker arms, head bolts) - oil changes were sporadic at best - if the parts look nearly new - the previous owners cared about the car - and left you with a good motor. You can do oil analysis and that can tell you a LOT about bearing conditions etc. for relatively little money (roughly the cost of a new oil pan gasket). If you do pull the heads - the presence or lack thereof - of a ridge at the top of the cylinder wall will also tell you a lot about what's going on with the motor's internal components. BTW - you can drop the oil pan with the motor in the car - again it's not that easy - but pulling the engine and trans is not the ideal way to spend a Saturday... I'm not a huge fan of compression tests - they tell you if something is bad - but a leakdown test is a lot better diagnostic tool. If you see low leakdown rates across the board - you probably have a good motor....
You can find what rear ratio came in it from the factory by looking at the codes on the tag in the storage box , my 95 auto came with the optional 3:07 I think the other is around a 2:59..
Tag looks like this is from my 93 Do a search on the codes you will find every option that was ordered from the factory.
'95 auto with 84k miles
