OK, I have a stock bottom end .030" over. I have the ZZ4 cam in it and Edelbrock headers. I did a 13.25 @ 104.84 mph. I then pulled the stock L98 heads and put on Trickflow 23* aluminum heads. While it was apart I siamese ported the TPI base. Now at higher RPMS the car pulls much harder, and keeps pulling past 6000 RPMs, but is a dog off the line. I went from 1.90 60' times, to 2.3. What gives?

 

How much did you port the base?

 

Really deep. Theres only about 1.5" of the divider wall left at the head side. I knife edged as best I could the wall to allow the air to transition nicelt into each port on the head.

 

I would guess a higher stall is in order.

 

Actually, I would put my money on the heads flowing too good. Anytime you have a fairly stock motor, and you throw super heads on it, the motor will lose the low end grunt. On the big end it'll come back as you've said, but stock type motors need to have smaller runners to create the low-end grunt. What kind of compression are you running? Unless it 10:1 or a little better those aluminum heads are also killing you- iron makes more power than aluminum on the lower compression motors cause the heat stays in and doesn't dissapte as quickly. Buddy of ours was running Dart iron eagles and switched to the aluminum version last winter. This year he lost .7 secs. switched them back to the iron heads, right back where the car used to be. My 2 cents.

 

Fairly stock motor?
Procharger with a ZZ4 cam, headers, and big injectors...

Not what I'd call stock.

 

The motor was rebuilt by the dealership under warranty. I've never had the engine out of the car. It should be running around 9.5:1 compression. I did the porting and the heads at the same time, so now I don't know which is the culprit causing me to slow down. What really bites is that the supercharger doesn't start makin any real power until after 3000 RPMs either, so I'm dead in the water off the line. Short of putting in a 3400 stall, any suggestions? I pulled the ProCharger off temporarily just to eliminate variables. Now the car is running 15.50 @87 mph. When it was stock it did a 15.18. With the 3.73 gears, it could do high 14's while spinning all through first and second gear. Now, with all sorts of mods, it goes 15's again. Anyone think it could be the port job on the intake, or is most likely the heads?

 

DUH...I did'nt read the sig. BUT, I still stand behind the theory of the heads. It's obvious the combo he ran before was working more n-sync (that sucked did'nt it) than it is now. I would bet your left nut that if that baby had a rpm intake and say a 750 she'd be into the mid to low 12's. I'm from the old school of the intake and carb combo, sure the new stuff gets great gas mileage and in a sence LOOKS cool, but if I'm gonna throw all kinds of performance mods at a car I like simplicity that has been proven time and time again. Not sayin I'm a slacker, but all the trouble it takes to have chips burnt and whatever else you fellas have to do, give me 2 hrs on the old set-up and she'll blow the doors off the EFI set up-considering everything else is similair. They're just not a layman set-up, who wants to go to college just so they can rod their ride?

 

IHI, I agree with ya'. This is my first attempt at rodding a fuel injected motor. I've built many a small block chevy setups with great success, but all of them had intakes and carbs. I just had to try my hand at the high tech hot rod game. So far I don't think I'm doing so good. I just bought a Pocket Programmer 2 and some blank chips, so I'm trying to dial thing in better. But considering both before and after the heads and intake, the car was using the stock chip I can't very well blame the tuning. I guess I'll just have to go and get a 3400 stall and live with the fact that my motor has a power band from 4000 to 6000 now.

 

Man,, you've got some other "problem area" beside the heads or intake. However, no larger than the TFS head volume is,, they ARE NOT hurting your bottom end. I've run 215 Iron Eagles on engines that pull better off idle than the 180's. However, siamesing the base I'm sure rolled off a good bit of grunt. Still,, you should be running at least 13.5s without the super charger. I swaer this is not a dig on you,, but you need to beg, borrow, or pay someone that knows what to look for with a scanner to "see" what's going on with your combination.

It's taken me about a year and a half to really be comfortable with fairly major modifications to this EFI stuff myself. I'm a huge carb fan,, but I tell you a ported LTR set up (not siamesed) on lesser flowing heads,, around and under 240 cfm at cam lift is VERY impressive - once you get all the gremlins worked out and the car dialed in.

Good luck,, I'll try and help if you can give some scanner readings.

 

I have Diacom and a laptop. Let me know what you need and I can get it to you. I watched my buddies GN drop a full second with nothing more than a chip change, so I'm fully aware of what the proper tuning is capable of doing. I just burned a new chip with the ARAP.bin file on it. According to G-Tech, that shaved 3 tenths instantly. I'd appreciate any help I can get with this problem. As we speak, I'm trying to get my hands on a stock intake, so I can pull the ported one off and see if that helps.

 

Well guys and gals, the problem was found. It was the siamese ported intake. It moved the powerband way too far up and caused all my off the line power to go bye-bye. I switched back to a stock TPI intake and instantly got a full second faster 0 - 60 mph times. Now its time to work on optimizing the chip tuning. I'm hoping to get into the high four second range with a perfect tune.

 

holy crap you ran a 13.25 with a 350, ZZ4 cam, 3.73 gears and a supercharger!!! Damn, I feel sorry for EFI guys. I got my firebird to run a 13.25 @ 108 with a "beer built" stock 350 with STOCK vortec heads, an RPM intake, comp cam and 3.73 gears! I'd say slap a carb on there, but since you already have an EFI specific SC and a bunch of money invested into the EFI setup, you're kinda stuck with it I guess.

 

Chris, I wouldn't consider it being "stuck with it". This is a new setup that unfortunately had some mismatched parts. I don't have the supercharger on the car right now while I'm trying to straighten out the mechanical issues. Right now I can almost stay side by side with my buddies 12 sec, Grand National. Once I finish tweaking the setup I'll put the blower back on. I figure it should go 11's once all dialed in. Thats not too shabby for an everyday driver that I'd have no problems with drivibg coast to coast in.

 

I'd check your actual compression ratio too. Many replacement pistons are "destroked" (less deck height than origionals)
usually .020" This is to maintain the stock cr with an over bore and some decking. Also if your stock motor used thin factory head gaskets and were replaced with .042" felpro's without
appropriate deck milling, your net cr may be a lot lower than stock.

 

Yeah really. I'm hoping for low 13s after porting these stock heads and higher stall TC. I want a SC to get into the 12s.