NosLaser

Hey all, I've been a member of this board for quite some time, and I've seriously begun the consider the possibility of purchasing a C4 and modifying it up to play with the big boys. I'm sick of hearing "Supra this, and Supra that." All these guys with more money than they know what to do with making cars fast JUST because they have money. I don't want to get a Supra because there are enough of them out there, and quite frankly, I'm quite disappointed with the attitudes of their owners. Oh yeah, more to my point, I don't think they'll be able to keep up with a Twin Turbocharged 383 C4 with spray on tap just in case. ;) I was able to extract 500HP from a 2.0 4 cylinder with very minimal mods and minimal money invested, so I'm ready to step up to a vehicle with more potential, and really get serious about making big power. Alright, a little background on what I'm looking for. I like to race on the highway. I like racing bikes, Vipers, Porsches, and other exotics, and have fared very well in my DSM. I want to build a Vette for the highway, and am willing to sacrifice low end torque for top end power. I would like a motor that can rev comfortably to 7500rpm or higher, and keep pulling harder and harder as the revs go up. I'm going to be on a smaller budget, and will be doing most of the fabricating and just about all of the work myself since I'm still young (22) and don't have the luxury of a trust fund or parents who paid for everything all my life. (A ZR-1 is out of the question ;) ) I guess my question for you guys, is what kind of heads fow the best on the LT-1 motors? Am I better of taking the LT-1 out, and building a motor straight out of a summit catalog (retaining fuel injection of course, and obviously not STRAIGHT out of a summit catalog, but you know what I mean)? What are some of the limiting factors of the LT-1 engine? How is the factory fuel system? What kind of aftermarket engine management systems fare the best on C4's? I'm looking to start with the newer style (I think 1991 and up) and I like the fact that they are really pretty stable at higher speeds; one of the advantages of going with a Vette over my other possibility, a Mustang, is that I won't have to change the suspension or brakes too much, and it's a much more stable vehicle. Plus the 50 cubic inch starting advantage doesn't hurt either. ;) I appreciate anyone who has read this far down, and any insight you guys may have on what I am looking to accomplish. I know there are other ways to do it (big cubed, carbed motor, etc etc.) but I have my mind pretty made up on going TT and efi. Thanks again, and any insight would be greatly appreciated.

:cheers:


[Modified by NosLaser, 6:20 PM 3/13/2002]

NosLaser

Oh, and one more dumb question...the 1991ish C4's, do they all have a removeable hardtop, or T-tops? I would prefer a solid roof if they made one, but I'm not exactly sure. Thanks again.

88-406

Why not just rebuild the LT-1 to handle huge dosesages of Nitruos. It wouldn't need to rev to 7500+ to kick some serious A**. I'd go with a DFI and some Big AFR's, solid roller then try and keep the motor looking stockish :D

I don't even think you'd have to give up any bottom end either! A 600HP Toyota would not be a match if your 3rd stage is 400ish or so.


KM

vader86

rebuild with better pistons, rods, retainers, RR, crank, a very agressive cam, straight pipes instead of mufflers and no cats. Bore the engine out to as big as it can take. Get as big a MAF as will fit on it, later C5 ones can be modified to fit i think. If it was an L98 i would say Miniram in a heartbeat, but i dont know if it works on the LT1 or even if its an improvement over the stock manifold.

bigger injectors, hiflow pumps, everything.

and 91s had a targa top


[Modified by vader86, 8:05 PM 3/13/2002]

Springer's LT4

All C4's have targa tops...


There was a thread or 12 on the forum about a twin turbo C4 making somewhere in the neighborhood of 1300 HP... your talking some serious cash, even with fabricating your own parts, but anything is possible.

bill mcdonald

Where would you mount the turbos?

pablocruise

:rolleyes:
joining the rest of us in dreamland?........

stuntman

Hi Aslan,

I'm kind of going through what you ask about, but I'm more interested in bottom end speed. I bought an '85 just to modify for racing. I spent $4K for the car.

I am stroking the engine to a 383 c.i. on a new 4 bolt block. The heads are being custom CNC'd by Air Flow Research. I got a super ram and base from Lingenfelter, as well as the new cam and roller lifters. I got a 52mm throttle body, an '86 computer with a painless wiring harness. I canned the air conditioning system, bought an aluminum "Be Cool" radiator and an accessory fan. I changed, replaced or modified virtually every piece of the car. I installed a 150 horse nitrous system, a 3:73 rear end, Hooker headers, Flowmaster exhaust, and an ATL fuel cell, a truechoice fire system and a roll cage. I had a custom dash made from brushed aluminum (I just installed today) with all Autometer Ultra Lite gauges. There are 2 Corbeau racing seats and Jim Deist is making my 5-point harnesses right now.

The car is for a racing league for professional stunt performers. The man to beat just bought a new Porsche twin turbo (at $180,000!!). He won with a '95 911 last year. With the new car, he's at 6.9 pounds per horsepower. At 525 horses (which is a conservative estimate) running at 3600 lbs, I'll be at 6.8 lbs per horse and bring it down to driving skills. Regardless, since I did almost all of the work myself and used up some favors, I have kept the cost at around $25K (not including the $4K for the car).

The car won't be exactly street legal here in California, but with a few connections, who knows! Pretty much anything fun is now illegal or currently being lobbied against. God forbid I get caught transporting a leafblower!

Anyway, the race is two cars head-to-head. You go through a 3 barrell slalom into a 450 foot drag to another barrell. You throw a flying 180 arouind the barrell and head back down the strip into a hanging tether ball to stop the clock. This is why I need the bottom end power.

Best of luck with your project if you decide to take it on. It has been a fun two months building this thing (yes, that's fast) and hopefully it will perform as well as everybody hopes.

Joe

NosLaser

Wow stuntman, that sounds pretty wild! ;)

As far as being in dreamland, ehhh...it's gonna take work, but I don't believe it's as far out of reach as you guys may think. I have a pretty good model to go by, as a friend of mine down here in Florida actually built the car I am talking about. He built a 1987 Corvette, twin turbo, and used an Electromotive system. The car made over 1200HP, and was used as his daily driver for 3 years down here, and 40K miles. The car ran great, was absolutely INSANE from a roll, and it's one trip to the track yielded an 11.5 at 165mph. For those who say I'm B.S'ing, I will find the videos, capture them on to the internet, and post them. Anyway, using his trials and errors, I think that I can put together something that will work really well, and the C4 is a very good starting platform. I plan on using a 366, which after doing some research, seems like it would have just about the best rod/stroke ratio of any Chevy motor available. A nice set of Eagle rods, some forged low compression pistons, maybe AFR or Edlebrock heads, stainless steel swirl polished valves, (I'm undecided on the cam) but I was figuring the engine would only have to rev to about 7200rpm max. Obviously the block would be done nicely; bored/honed, align honed, decked, O-ringed, I'd have the inside moly coated for better oil splashing characteristics, knife-edged crank, balanced bottom end, etc. We have a VERY good local machine shop (Mesa Machining) that does world class work at very fair prices. I can port heads myself and do combustion chamber work myself, so that shouldn't be too big of an issue. I'd have to look at the factory intake manifold more closely, and decide what needs to be done in that category. Ideally, I'd like as large of a plenum that will fit under the hood, and as short of runners as possible. Figuring custom headers tthat both reap efficiency, and actually fit under the hood will be a tough proposition, but with the help of a friend of mine that designs them, we should be able to pull it off. I was planning on using the FelPro system (used to be called the speedpro, and now I believe is called something else, like F.A.S.T. or something) which is decently priced, and pretty tuner friendly. The fuel system would be a pretty straight-forward affair; a 1/2 inch pickup with a 300 micron in-tank filter, -10 out to a Y fitting and twin -8 lines to dual Bosch pumps, and then -8 lines to custom fuel rails, and a -8 return. An SX, Aeromotive, or some other nice quality fuel pressure regulator should take care of pressure needs. Turbo sizing would be the next task, and that should be relatively easy, with some pretty simple numbers having to be worked out; same with injector sizing. McCleod makes a triple disc clutch that will more than hold the power, even with a stock-like pressure plate for minimal pedal effort. The stock tranny will hold power, as will the rear-end (remember, this isn't going to be a drag car that is ever launched hard, it will be made to go fast from a roll) and the only thing I'd worry about are half-shafts, but that will be a part you plan on having extra of. ;) In all honesty, I think the task could be accomplished for ~15 grand over the price of a 1991 Vette, which I figure if I shop around, I can get for 10 grand for a good running, well maintained example. Obviously, this is something I can tackle over time since I plan on building a motor on a stand (not using the LT-1) so the car will only go down to get the motor and clutch transplant (the turbos, headers, etc will all be mounted to the motor prior to it being dropped in.) Oh yeah, I also have a pretty cool advantage in the fact that I can internally gate the turbos to save space by not having to run an external wastegate setup. I'd use a manual boost controller, custom front mounted intercooler, and (as much as I hate saying this, they are actually good pieces) Greddy type R blow off valves. I just wish they would change the name because I hate saying "type R" but they really hold boost rather well. Additional power will be had through a single stage NOS systems ProFogger direct port kit with soft plume nozzles and sapphire jets. I seriously doubt the nitrous will ever be employed, but it sure would be a cool afterthought. ;) The whole project would take time and money, but I think with a Vette, in all honesty, all kidding aside, you have a very good bang for the buck proposition. Chevy motors are bar none the cheapest motors to build on the market. The rest is simply buying the neccessary parts, and fabricating the things that aren't just direct bolt ons, which I'm actually pretty adept at doing. They make all sorts of cool aftermarket cooling system upgrades, etc. that I don't think the whole project would be too difficult. For those who took the time to respond, I appreciate it. I want something pretty unique, and I like the whole sleeper appearance, so the car will remain VERY stock looking. This post was simply stuff off the top of my head, and things may change as I go forward with plans, but I wanted to get an overall feel from those of you who may have tackled similarly in-depth projects, and any "Corvette specific" hurdles I may encounter along the way. Thanks again.

Regards,

merrick

Damn, write a book(like I read it). Plan on spending $10,000 plus on a turbo setup, just for parts. You may just want to get a Callaway vette instead and save a headache.

bill mcdonald

yeah, but where are you going to put the turbos?

NosLaser

<<<Plan on spending $10,000 plus on a turbo setup, just for parts.>>>

How do you figure? I can prolly get both turbos for well under $1500, custom headers will prolly run me another $1500, and the front mount intercooler setup will run another $1000. I have a very good hookup from being in the business, and can get parts pretty cheap, and will be doing all the fabricating myself. The turbos will prolly have to be mounted down low; I don't have a Vette yet so I really can't tell you EXACTLY where I'm going to mount them. Remember also, I will not be using the LT-1 motor, and will also be going with aftermarket engine management, so I can prolly clean up the engine bay a bit more to create some room.

Hi-psi

Turbos + stock LT-1 compression = boom

It's really not worth it to boost a stock LT-1. The static compression ratio is already so high when you factor in the increased cylinders pressures result from the boost, you approach the knock threshold of pump gas rather quickly. You would either have to run low boost or race gas all the time. The other option would be to build a motor with about 8.5-9.0:1 compression, slap a couple of TE-44's or TE-60's on it and let it ride. You could use MSD 50lbs injectors, and a staged double pumper Walbro fuel pump setup with the second pump coming on via a Hobbs switch with boost. For added insurence you could have an alcohol injection kit also. You would most definately need some form of aftermarket fuel management. I would NOT go with Accel DFI. DFI was good when it was the only thing.....and it's cheap,...but you don't wanna skim on the fuel. I would put a Speed-Pro system on it. This sytem is a speed density system, and uses a wide band O2 sensor for tuning. With a good 377 or 383 I don't see a reason why it wouldn't make over 500rwhp on pump gas and would be damn impressive on the torque.

dgoodhue

OK I would guess $15K. $5K for the above, $2-3K for fueling, and $5K for a forged motor rebuild. If you want aftermarket intake (L98) or heads, cam , valve train (if you want to rev it) add more. You will have to deal with the drivetrain issue if you making a lot power. It is difficult to mount the Turbo down low because of oiling issue (the callway has an external oil pump for the turbos) The front of a C4 is pretty cramped for intercoolers.

A callaway TT already has a stout forged short block, turbo, oiling, and some fueling issue are taken car of. A callway TT can make 500+ rwhp with a better air intake and free flowing exhuast and I have seen some making 620 with mild molds (intake, heads) If your planning a 1200hp TT then want to just go with a custom setup, what are your goals?

No Go

Unless your heart is set on twin turbos I don't think you really need them.

Look at the top end race vehicles in Silver State, etc and many of them are naturally aspirated.

Nearly everyone of the turboed or supercharged cars in One Lap of America blew up. Even a seemingly bulletproof 351 Mustang with 580 RWHP failed before the end. This changed my mind for natural aspiration.

Good luck on your goal. I have similar goal and believe the C4 corvette is the best vehicle out there for the average joe that wants to go quick and fast. Heck with simple addition of HOT cam in my LT4 I'm hoping for 180 mph.

:)

NosLaser

<<<Turbos + stock LT-1 compression = boom
It's really not worth it to boost a stock LT-1. The static compression ratio is already so high when you factor in the increased cylinders pressures result from the boost, you approach the knock threshold of pump gas rather quickly.>>>

I'm guessing you didn't read my novel up there did you? I wouldn't even be using the LT-1 motor. I have a LOT of experience in turbocharging, so that wouldn't be an issue. I was really posting to get feedback, and see if anyone could spot any weaknesses in my plans (such as the fitment of the turbos and the oiling issue, which are both good things to consider.) I would never be happy with 500HP. My Laser makes 500HP. The whole reason for getting a Vette and going Twin Turbo is to go above and beyond my current car's capabilities. I can wring about 700HP out of the Laser without too much trouble, however it wouldn't be nearly as reliable as a high HP Vette simply because you have quite a bit more displacement to dispurse the power among the cylinders. I am looking for 1000-1200+ HP, or else I would be considering some of the previously mentioned ideas (nitrous motor, etc). I want to build an animal, I have the resources and the know-how to do it, and after really looking at it, it doesn't seem like it will cost too much more than getting my Laser up to that 700HP mark I was planning on. I'll keep you all posted with updates, or new ideas as I come across them.

The Dingo

Please do. There are a few of us here who have kicked this idea around and would like to do it one day :).

1991Z07

Well, you may as well use someone elses experience to complete a project as ambitious as this one. Callaway already did a car like this with the Sledgehammer project.

Heres the link to the article on their web site http://www.callawaycars.com/Corvette...er_article.htm

Fitting those big turbo's in there was a project in itself. They placed them behind the front wheels (behind the gills) and had to bore 4" holes through the frame to feed them. It isn't out of the realm of possibility, but Callaway spent around $400k to get the Sledgehammer working right.

I wish you luck in your endeavors. I was actually playing with this idea for a while. I need about 800-850 HP to cruise effortlessly at 200 MPH in the Open Road Racing environment. A turbo car could have done it easy (since the base motor is a 427 SBC), but I can slip an ATI supercharger with intercooler on it for $5k. The turbo route is much harder, more expensive and more than I think I want to tackle at this time.

Keep your goal in sight and just work towards it. Keep us informed..

scorp508

Buy a ZR1 and go 176+ mph all night for 24hours straight if you wanna. :)

Hi-psi

the SledgeHammer.






[Modified by Hi-psi, 12:42 PM 3/14/2002]