Howdy, I dont have a c4 atm but I’m thinking about getting one and I’m thinking of possible mods and upgrades. Now I’d rather not go through the expense and complication of ls swapping one and just keep the LT1 but through all the reading I’ve done there isn’t much on what can be done in terms of serious upgrades, cause as one does I was thinking a super charger with boosted internals. As one one does anyways lol. I’m not super experienced in this so help would be appreciated

 

You could just pick up a ZR1 and start with a very hot Vette.

 

but those a rather expensive tho

 

Hot and thrifty rarely discribe the same car. Occasionally the are good deals on hot well sorted cars. You should in look or place ad in C4s wanted / for sale sub forum.

 

I'm an L98 guy, but there are more similarities than differences between gen 1 and 2 SBC.

As you said, there's always boost! There are many people running super or turbocharged LT1s making 1000hp+. Of course it's not going to be as easy as making power on an LS, but it still isn't terribly hard. It might be easier and/or cheaper in the long run to LS swap it, but swapping the ECM has some consequences like some dash gauges that won't work. If that doesn't bother you, great.

If you want a manual, LS/T56 swapping an auto C4 might actually be a good way to go, as the manual C4s command a premium (especially for the 6-speeds, which were only offered 89-96).

 

LT1s have tons of options for upgrade paths. You can buy good aftermarket heads for them, you can get stroker kits to increase displacement to 396 with the stock block, you can buy all kinds of cams from mild to wild. And of course you can add a supercharger if that's your desire. For the latter, you can get rotating assemblies with very stout cranks/rods/pistons and you can convert an LT1 to a four-bolt main with splayed bolt pattern, which is probably handy if you're really going to push serious power numbers. But even without boost, you could put 500hp to the wheels if you're willing to put up with a serious cam (most likely requires 3.73 or 4.11 rear gears - will be really fast); or ~410-420rwhp if you want to retain stock gears, decent streetability, and a useful 6th gear at legal(ish) highway speeds. If you are looking at LT-engined cars, the 94-95 cars have PCMs that can be recalibrated with a reflash using cheap hardware and software. The 96 is similar but requires fairly expensive software because it is OBD2. I would look for a 95, since it comes with a vented Optispark and better ABS. However, apparently the 95/96 automatics have an update that is prone to failure. This isn't an issue if you're looking for a manual, of course.

 

thanks! I’ll keep that in mind

 

I wasn’t aware of this! Thank you very much

 

There's a useful book to get a start on LT1/4 upgrades: How to Build Max-Performance Chevy LT1/LT4 Engines by Cottrell and McClellan. It's not new anymore, but it's a great starting point for your knowledge base.

 

thank you very much! I’m not looking to make a drag strip legend but a fast and fun street/daily with more power then the stock 250-330 whp

 

The L98 and LT1 internals can handle some boost and still live a long time but you have to start with a healthy motor. Many people on this forum have stock internals with superchargers putting out around 500HP+ for years and still running strong but their boost levels are not very high, which is fine depending on your goals. Since you're just looking for a fun street machine, I think low boost is your best bet since the torque will definitely be there and torque is what makes street driving so fun. High HP levels tend to make cars less driveable around town (streetable). Another option would be cam/heads/headers which could give you approx the same power from an NA setup and still be very reliable in the long-term, and streetable enough. Of course the key to longevity is not to get too crazy with the power levels. You can go higher than 500-600HP with the L98/LT1 but you must build it if you want it to survive the beatings. On the other hand, stock LS internals can handle 800+ HP and are legendary in the tuner world.

 

As someone who owned a 396 C4 with around 410-420rwhp, I can tell you that this amount of power transforms the car into something completely different than a stock LT1/4. It's an order of magnitude faster, but the chassis easily deals with the extra power. A similar build today would entail AFR 195 Competition heads, a smallish cam with aggressive ramps and high lift (I had a custom Comp Cams grind), and a stock or gently ported stock intake. You could probably make 390-400rwhp with a pretty gentle idle, or if you can live with a little bit of a lumpy idle you can probably get around the power I was seeing.

 

How would a person go about this ECM re-calibration if they owned a 92 or 93 model?

 

I am working on what you are thinking about doing. I am just starting with an LT4 car... so 96-6-speed. Already has some decent upgrades over the LT1, but nothing game changing. With a basic Procharger Kit and Cat-Back exhaust it makes 450hp at the crank. All street manners perfectly intact. All gages work, AC, cruise, etc. I am stacking up parts to make her quite a beast later on (Heads/Cam/Intake/Throttle Body/Headers/Fuel Pump/Injectors). I will be keeping the boost at a reasonable 8-10PSI on stock internals. It will always be in the back of my mind to go 383 or 396 should it let go.

Don't worry about forged internals unless you are going north of 10-12PSI and aren't willing to keep timing and fueling on the safe side.

Which brings me to my question, what are you trying to achieve and what are the constraints?
The cheapest car you can make fast enough to be fun?
A project where there are plenty of upgrades to do over time and it keeps getting faster as you go?
Do you have a HP goal you want to find a car as a platform to make?
Do you have a time goal?
Budget for car and mods?

The C4 is a great platform for any of the above. It is a notch above Camaro/GTO/Mustang in that it is already a better handling and braking car out of the box, but the IRS hurts a bit for drag racing. Though, plenty of members here with respectable time slips on an IRS. It also still has a SBC under the hood so, options are plentiful. Did I mention the price of a reasonable C4 is still, well reasonable for the platform you get. If you think you may go LS, just get a C5 and save yourself time and hassle.

Or just buy mine and I will go buy a C7

 

PROM burning equipment and do your own
Mail order a PROM
Convert to EBL

 

Thank you. Based on your recommendation I went out and bought this. Great read!!

 

This is very true. There are tons of ways to upgrade an LT1 car. But I think before you start planning on mods you should set goals for the car and a budget. If you want to build a drag car then an early style C4 with a 4L80e and a LS swap if tough to beat. But if you want to autox the car that level of power and weight aren't wanted. An Lt1 with a cam will be plenty assuming you have a 6 speed car.

Me for example, I have no interest in autox and I like automatics. So big LS with a good trans and nitrous was the only way to go. But I know I would get my butt handed to me on a road coarse. I prefer the 1/8 mile.

 

There are 9 & 10 second LT1 cars out there why would he need an Ls?