Because of the higher compression and lighter pistons I am told it is not worth supercharging a LT4. Anyone have one or comments

 

If you decide to do it go to Greg at www.blowerworks.net. Quality kits that address your problem using Gaseous Intercooling as way of fighting detonation.

 

Thanks right now looking at the HP per $ it does not look like it is worth it.

 

well... you could buy my kit for $2750 and then add an alky injection kit. For about $3600 in hard parts (blower kit, injectors, chip, alky injection kit) you'd be ready to go. Just a suggestion...

 

Thanks, still trying to get feedback from LT4 owners who have supercharged their engines. The lack of responses seems to confirm that its not a good idea to do so.

 

Mine probably would've survived 7 psi for awhile. Didn't like 9-10lbs. though

 

Its a lot of $$ to get the power you could get from a heads and cam swap. That's probably why you don't see a lot of them. I'm building an LT4 for my setup, but it is around 9:1 compression with a forged bottom end.

 

For you LT4 owners I asked Greg at Blower works for his opinon and I have posted his response. I do plan on road racing the car a few times over the year so we can put this to bed:
From: greg@blowerworks.net

Hi Kevin,

Thanks for your inquiry about your LT4. The LT4 with its' higher compression ratio actually responds quite nicely to being supercharged. You get more bang per pound of boost with the higher CR. And yes I do restrict the boost to a lower level, around 6 to 7 pounds of boost - you do not need as much to obtain good results. The 6 to 7 pounds will result in an approximate 35% increase: 420 becomes 567. In order to obtain those results without detonating you must inject a 50/50 mixture of water/alcohol at a rate of 15 gph. I call that "Gaseous InterCooling" and it's a must on the LT4. That said let's look at the down side: particularly in your case if you plan to go road racing. The downside with your compression ratio and cast pistons is that even a small amount of detonation at higher engine RPM's will crack a piston - then you are done! Most of the guys who supercharge their Vettes are garage queens with an occassional trip to the dragstrip. No problem - they are not on the throttle long enough to seriously heat the engine heads to saturation. In your case though I would be worried - first the 2.5 gallon bladder is going to be emptied in 10 minutes of WOT operation. Second with your sustained WOT operation you will likely heat the engine to the detonation point - and as I said any detonation above 4500 RPM will crack a piston.

Your LT4 PCM does have a spark correction vs. MAP vs. coolant temperature which I really have not had to use. It is possible to dial in a lot of spark correction as the engine heats up and thus avoid detonating but it would be with a corresponding power loss. Still you would have to address the reservoir size. I make a rear clip stainless steel tank but it has become very expensive at a $1000.00. It does hold 6 plus gallons which equates to 24 minutes of WOT operation but we have now a very expensive supercharger system.

My answer to you is to leave it normally aspirated if you are going to road race it unless your pockets are deep enough and your mind set such that if you had to rebuild the engine you wouldn't be upset.

Best regards,
Greg

 

Have a twin turbo LT4

 

would like to hear more about that one...thanks

 

So would I

 

As would I, details please...

 

Well i have an Lt4 and was going to just supercharge it and after spending lots of time reading others opinions i think that if you are looking for a quick 150 n20 would be the safer an easier way but if you want to invest more money the lt4 is the perfect platform to go all forged internals and then put gregs 12psi lt1 kit on. His kit is listing 600hp on the lt1 so a stroked lt4 should be pushing 650-750 hp or even more i am in the first stages of this project fixing to puchase rotating assy and get the engine built i will let you guys know how it goes

 

There's a ton of guys on here running blown lt4's but most of them are rebuilt to use forged pistons and strokers for more cubic inch. You can run a blown lt4 without problems even with cheapo pistons; it's just in the tune and keeping boost at a reasonable level. I can't imagine that the corvette lt4 shortblock is any more fragile then the crappy 5.0 mustang shortblocks. There's ton of f/i guys that beat on those like crazy with hyper pistons and all. If you keep boost in check to compensate for the added compression or add alky injection, I'm sure you'll be fine. I can't imagine nitrous being any easier on a shortblock then fi at reasonable levels. That's why a considerable amount of the big time class racers have gone turbo or blown from nitrous. It's easier on parts.

Matt, I was running 10psi on a 383 and was over 500 rwhp without even a decent tune and I beat on that thing every day. The car is currently down getting a bigger blower and more boost to hit 650-700 rwhp. Also, if you're going to get a stroker, make sure you get the t trim blower upgrade, minimum. That blower is good to about 600-625 rwhp on our lt4's. The s trim will probably run out of steam about 550 rwhp or so. I'm currently going with a vortech ysi. I'm glad that I am hooked on blowers because in one session, I'd probably empty a 10 lb bottle of nitrous based on how much I beat on this thing. That would get very expensive.

 

As Greg has stated, for my particular situation, where I plan on road racing a few times a year, supercharging the stock LT4 is not wise.

 

Well it a been gone through with scat rods, eagle crank, JE pistons 40lbs injectors custom intake, 2 garrett ball bearing gtr 30s u can see all the pics of my corvette and cobra r with a single turbo on forcedairtech.com