Would ported GT40 intake be too big for stock heads?

black143 · Apr 22, 2004

Hey Guys,

I have a chance to buy a ported upper and lower GT40 intake set for $300. The only problem is I have stock heads so I was wondering if this was going to help at all (or possibly hurt)?

I currently have full exhaust, CAI, Underdrives, brand new 19# injectors in regards to the motor. I was going to get this intake set, 1.7 Crane Roller Rockers, a 65MM Throttle Body, and an AFPR.

I have an 88 GT so I'm still running Speed Density. Anyone see any problems with this setup I've listed? Thanks guys.

Mavrick · Apr 22, 2004

I'd go ahead with it.. all the bigger the improvement will be when you get new heads! Not sure how it will act with SD though.

black143 · Apr 22, 2004

Mavrick said:
Not sure how it will act with SD though.

I've heard I can do everything except a CAM with SD as long as I tune it right. I've heard of quite a few guys running SC's and Turbo's on SD cars. Just have to make sure its tuned right (though I'm not exactly sure what that means). If anyone knows how to tune a SD Car the correct way, I'm all ears.

N8Miller · Apr 22, 2004

yeah, go for it. it wont be too bad with SD. get a set of mild heads...nothing to wild though. Like said, when you do get some heads, then you will notice it like a kick in the crotch (but in a good way )

black143 · Apr 22, 2004

Well this car is my daily driver so I need to make sure it drives pretty well. I dont want to have a fast car that bucks and surges because of the SD.

Does anyone know exactly how to tune a SD car when you do engine work? Also, anyone have a power estimate for my car with the setup I will have (Intake, Roller Rockers, TB, Exhaust, Underdrives, etc)?

Thanks all

RYC CUKR · Apr 22, 2004

I have a ported GT40 on my stock E7s and I noticed a little difference but not a huge one. I would say go for it and if and when you put on heads you already have it done. Before I put my ported intake on my dyno #s were 202 hp and 271 ft/lbs I believe. I think it is in my sig but I can't remember I know have 1.6 roller rockers, O/R x pipe and the ported intake but am too lazy to take my car down to have it dynoed.

black143 · Apr 22, 2004

I'd be really curious to see where your numbers are at because your setup would be REALLY close to the setup I would end up with, except for your MAF and my SD.

tmoss · Apr 22, 2004

Depends on the quality of the porting work and how large the runners were ported to, so try and find out how they were ported - dimensions and whether it was a simple gasket match or true runner porting.

Na5.0HO · Apr 22, 2004

Tuning Speed Density cars is kind of a pain in the a**. My '88 was SD before I converted it to Mass Air and ran horribly (prob cause the previous owner put in a bigger cam lol). Neways, there's 3 was I know of to tune. Set the timing depending what you have done performance wise (prob between 12 and 14 degrees), adjusting the TPS sensor on the TB and adjusting the idle positioning screw on the TB (Not sure if that's actually what it's called). Neways, "screwing" with these 3 components is the best way I managed tuning. Hope this helps.
Jason

black143 · Apr 22, 2004

I wonder if my idle screw is why my car's idle is always jumping around. It'll go to about 800 and slowly climb to 1500, and drop back down (repeat). I need to set the idle to the correct setting.

Jason - Did you resolve your driveability issues when you converted to MAF?

Na5.0HO · Apr 23, 2004

The MAF conversion made the world of a difference, but I'm guessing it is because of an aftermarket CAM. (Not positive it it has one... but after the conversion is sure idle'd like one). My favorite part was that annoying surge is gone. 800 - 1200 rpms was the best tune i could get!! Just takes lots of tinkering. Good Luck.
Jason

87gtconv · Apr 23, 2004

There is a procedure for tuning the SD motors and what you do is first set the timing ( I use 14*), then turn off the engine and unplug the air bypass solenoid on the TB, start the car up and adjust the idle screw to get 850 rpm's, turn off car and plug back your air bypass solendoid. Now adjust the tps from .95 volts to .99 volts, disconnect the battery for 5 minutes and then reconnect and start up and drive away!! If this does not get U a satisfactory idle you need to clean out the TB and solenoids and or look for vacuum leaks! Hope this helps.

black143 · Apr 23, 2004

87gtconv said:
then turn off the engine and unplug the air bypass solenoid on the TB, start the car up and adjust the idle screw to get 850 rpm's

My car wont stay started if I have the IAC unplugged. I always wondered what exactly people meant by this. If I dont plug in the IAC, my car will not start.

My timing is at 12 so I might bump that up this weekend and my TPS is at .98V so those two will be good. I did notice screwing with that dang idle screw really makes a lot of difference.

87gtconv · Apr 24, 2004

Sounds like U got a bad or stuck IAC to me! It should run pluged in or not!!

black143 · Apr 24, 2004

That makes me nervous because the IAC is only about 6 months old. I Just took it off the other day to clean it and its the cleanest its ever been. If I have my car running and unplug the IAC it will die. If I unplug the IAC and try to start my car, it will start and immediately stall.

proxses · Apr 24, 2004

If it starts, then immediately stalls, then the throttle blade needs to opened up a bit. Turn the idle set screw a bit at a time until it will start and run without the IAC.

sidewayzisbest · Apr 24, 2004

i have that intake........when i put it on i had just 3.55's and shifter......when i put the intake on i also put the full exhaust mass air and other tiny stuff and i noticed a pretty impressive difference for the money i put in....and makes engine bay look cooler =D.....

but to add on the thread =D should i get a new tb lol 76mm mass air & ported gt-40 but stock tb =/

sweet93hatch · Apr 24, 2004

My idle on my 93 is the same way. I was putting air in my tire the other day and left the engine running. I idled up to 3500 all by itself. Thats insane. It sounded like a ghost was trying to launch my car. Bad IAC? Possibly just a throttle adjustment? My car lopes and barely stays running with it unplugged.

black143 · Apr 24, 2004

proxses said:
If it starts, then immediately stalls, then the throttle blade needs to opened up a bit. Turn the idle set screw a bit at a time until it will start and run without the IAC.

I will do that and see what happens. I didnt know the car was supposed to run with the IAC unplugged. Thanks for all the info.

As for the intake, I think if I get the intake, I will definately do the lower plenum as well. I was reading tmoss's website on how restrictive the lower intake is. We'll see how much I get out of it. I gotta do something maintenance stuff first though. Such as fix my dang cracked engine mount!

Would ported GT40 intake be too big for stock heads?

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