I finally recieved answers from Scoggin Dickey and their Stage III LT1 to LT4 conversion (CNC Porting) will not provide the numbers I hoped for (the kit will provide an additional 55-65 CHP I was hoping for an increase of 100 CHP than than). Are my goals unreasonable for a $2,500 to 3,000 mod? Is there a better cam/intake/head choice for an A4 LT1 with a 3.54 rear? I must retain streetablity since it is my daily driver, however, I need a performance increase.
I am not interested in blowers or nitrous at this time.
Long tube headers are on my to do list, I am just waiting to see where I will be stationed next, (Kalifornia, Mississippi or Virginia). I am hoping for Missippi or Virginia I already was sentenced to the PRK for 8 years. (No offense to the current inmates)

Thanks,

Mike

 

Summit has a LT4 conversion , consist of cams heads and and intake. They state it will "support 450 hp" I'm not sure that marketing jargon, bu it runs about 2100 dollars... I'm suspecting you would or should get at least 50 with it.

Maybe others can chime in and share if they have used this upgrade.

Mo

 

I will check on that, however, if it is the GM hotcam, 1.6 r.rs, LT4 intake and LT4 heads it is good for about 45 hp accroding to Scoggins Dickey.
I know that this is a decent about of HP for a moderate amount of money however, I was hoping for 400 from the motor and then if/when I install LT headers and exhaust I will have a decent performing car. I always wanted a Vette however, I am getting resigned to the fact that my brother-in-law is going to blow rubber on my hood when he finally pulls his Cobra out of the garage this spring.

Mike

 

I am currently in the process of putting together a similar version. I decided to just have my LT1 heads & intake done to stage III by percision porting, adding an LT4 hotcam, 1.6RR, lifters, ST headers, electric water pump, & timing chain. The total cost of this is hopefully going to run me no more than $3000. Should be good for over 400 HP. If you want to talk to an expert about LT1 conversions, email Nathan Plemons, I was going to go with the LT4 heads but for the money I decided to go this route after conversing with him.

Good Luck with the conversion whichever way you go

 

Do you know how many HP your heads, and valvetrain mods were supposed to be good for?

Mike

 

Check out this place, I think this might be kinda what you are looking for: http://www.eportworks.com/LT1LE3.htm
Also, Bob at Precision Porting is running a deal too, his heads make pretty good #'s and I'm sure he can tell you which cam to match up to the heads to get the #'s you are looking for:
http://precisionporting.com/index_files/Page441.htm

 

Do yourself a favor shoot for a quarter mile E.T. goal or a Rear Wheel horsepower number. I say this because these are two things that you can actually measure. Unless you have an engine dyno you can't measure crank horsepower so you're simply guessing.

Let me make sure I understand what you're saying. You want 100 more crank horsepower than you've got right now, but you want to do it with stock exhaust and later go with long tubes? That's really not the most reasonable goal since you said it still needed to be streetable. The stock exhaust manifolds are very restrictive. The more aggressive your cylinder heads and cam the more restrictive the stock manifolds will be.

FYI the Hot Cam kit is worth 40 REAR WHEEL horsepower on STOCK LT1 heads with STOCK LT1 manifolds. If Scoggin Dickey tries to tell you it's only worth 45 using ported LT4 heads then they must have some really crappy heads. Unless you need every last drop of performance out of the car, stick with your LT1 heads and have them ported. You get a much bigger performance for the money ratio than having to buy LT4 heads AND having them ported.

If you want to see what an LT4 Hot Cam can do, here's what the dyno graphs look like over a progression of several different stages of modification. You should find it very interesting.

http://www.wku.edu/~nathan.plemons/h..._corvette.html

Other areas you might find interesting are my web page in general

http://www.wku.edu/~nathan.plemons/

And my building LT1 performance page

http://www.wku.edu/~nathan.plemons/h...rformance.html

These pages are not the holy grail for modifications but they contain valuable information to help you make an informed decision. If you decided you want a more aggressive cam than the LT4 Hot Cam that's perfectly fine, just make sure you know what all the specs mean. You can call comp cams or crane ten different times and get ten different answers as to what is the best cam for your car. The best thing to do is to talk the experts here on the forum. Personally I prefer a high lift with a relatively short duration. This gives the best driveability along with your power.

Oh and what year is your brother in law's Cobra? If it's anything less than an O4 I really wouldn't worry about it if he's stock.

 

Nathan,
They stated that their Stage III kit was good for +55 to 65 HP. I replied trying to quantify this and asked if it was CHP and he said, YES!
This means that their ported head are only worth +10 to 20 HP over stock.
If these are rear wheel HP these are decent increases and meet my expectations. Since in my calculations 355RHP is more than 400 Crank horse power.
So to answer your question, I want about 350 HP to the Rear wheels.
Mike

 

Here is the post from Scoggins
Michael,

I've listed the hp increases below.

1. Do you have dyno figures on your LT1 to LT4 conversions? +25-30hp

2. What the HP increase was (over stock LT1) for your Stage II kit KITSDLT4H? +45hp

3. What is the HP/Torque increase on your Stage III Kit KITSDLT4CNCH? +55-65hp

I would really consider getting you ECM programmed with a higher rev limiter, and keep the gears you have now.
Here was my reply.

[COLOR=DarkRed]The way I read your response in that the Stage III kit installed on a 1995 LT1 will put out about 355 to 365 crank horsepower and only 10 more HP than the Stage II kit. Am I interpreting the information correctly?

Why should I keep the 2.59 I hate the low end performance of my Corvette. Stock it really comes alive at speeds that will get me thrown in jail.
I really appreciate your help



Mike [/COLOR]

And here is the final email

Mike,
You're reading the dyno specs correctly. All LT1/LT4, and the LS motors all start making power at 3000rpm + . If this is a toy, grab those 3.54's. If you're wanting to retain decent gas mileage and add power keep em'. We've built Vette's before that had enough power that the ring and pinion size didn't make that much difference. You would be amazed as to what 65hp does to the bottom end performance.




So once again I will state if these are RWP I will be ordering the parts, however, if they are in front of the firewall gains I need to look elsewhere, for now.
I would rather bolt on new parts and have to worry about someone messing up my install. I keep reading and hearing about "reputable shops jacking up someones ride!



The Cobra is an 04 and I am supposed to help him with a pulley install when he gets back from his deployment.

Thanks,

Mike

 

With an auto trans that's gonna be a little harder to get but certainly far from impossible.

A friend of mine had an LT1 car with a really aggressive cam. I forgot exactly what the specs were. Anyway at the time I was making 336 to the wheels using my LT4 Hot Cam and long tubes. He had long tubes and put this really aggressive cam in his car, he only made like 325 or something. Meanwhile he had less low end grunt and less fuel economy. Later we both installed cylinder heads. Techincally speaking my heads were slightly better. They both came from the same place but mine had larger, better valves as well as a few more little tricks because I'm real good friends with one of the guys who worked at the shop. My heads had better flow numbers, etc. Back to the dyno I made 365 to his 380 or so. What this proved to me is that it really is the combination of parts that matters. His heads were a little bit worse, but his more aggressive cam made up for it and he had the better combo. With my heads he probably could have made 390 or 400. With stock heads though my cam was much better suited to the combo.

With stock manifolds his cam would have likely made even less power than my Hot Cam because it would have been choked even more. Cams really like headers. I would honestly recommend that you get headers before heads.

When I had my car with just the cam installed I was making 313 horsepower. I talked with Brian Tooley, the owner of Total Engine Airflow and asked him what I should do next. He sells cylinder heads, not headers. He told me to buy headers first. He said that with aftermarket heads the engine would be so restricted with stock manifolds that I wouldn't have been happy. I didn't know any better and would have gladly bought a set of heads from him if he said that was the next path. Instead though he threw away a sale because he knew that I would be happier with headers first. To me that showed a respect for me from another performance enthusiast. He didn't just want to sell me a product, he wanted me to be happy with the product. I try to do the same. I don't sell any products so I have no personal stake in anybody's modification path, I just want people to be happy. Ultimately I did get my cylinder heads from TEA because I knew I could trust them.

 

Yes, I know all about too much cam, large ports and valves. When I was in High School I rebuilt 62 vette 327 fuelie that a friend broke some piston in. I sold the FI unit install TRW forged pistons, ported the heads at my grandfather's shop. He told me to leave the ports stock, however, I knew better and went for flow. I then ordered Cranes hairiest solid lifter cam and installed the engine in a 64 Malibu SS Vert with a glide and stock rear. My girl friend Pontiac T1000 (a chevette) would spank me until 45 miles an hour. The engine was not worth a darn until I installed a 4.56 rear, turbo 350, and a high stall converter. I was never able to get the Power brakes to work (not enough vacuum at idle).

 

Prior to my 385 stroker motor I had a mild cammed 350 that was making 350/351 to the rear wheel. Here were the prime components:

Stage 3 heads from CNC
MORE Performance baby cam (210/224 w/.531/.534 lift using 1.6 RR's and 112 LSA)
1.6 RR's
275-16 R Lifters
TPIS Long Tubes
B&B exhaust w/3" x-pipe
Breathless Rammer (piece of crap)

This was a very streetable combination that ran 12.7 @ 111 mph on street tires and me driving (not my cup of tea)

Mike

 

Did you have an A4 with those Mods?

Mike

 

6-spd and stock 3.45 gears at the time.

 

You had a manual thats what I thought. How much more duration did you cam have than the hotcam? In my experience manuals are more forgiving than autos when it comes to cam shaft selection. I picked up a 3.45 Dana 44, I am going to replace the oil seals and U-joints before I pop it in and I have LT headers and exhuast stuff on order. Now I just need to find the valvetrain/head combo that is right for me. I appreciate everyone's input in my quest for a C4 that is not embarassing off of the line.

Mike

 

what about simple less expensive drive train mods? what is is that u want from the car? do u want it to have a 200mph top end , or are u just looking for something that will run the 1/4 mile in an impressive time and still maintain daily driveabilty? I think this issue is often over looked . Drive train mods can cost u much less than engine mods and you will realize great 1/4 mile gains even if your motor is completely stock. For instance,. .a stock 93 LT1 will run about a 14sec 1/4 mile give or take 3/10's... By changing the gear ratio to a 3:54 and adding a 3000stall converter and maybe putting a transgo shift upgrade kit in the tranny , that same stock motor will run about 12.9 in the 1/4mile give or take a 10th . and still has all the daily driver attributes in tack. So i guess is all about what u want from the car. THIS may not be your answer,... but it is something to consider!