I've seen a picture on the forum of a car that was modified to have a second intake on the top on the intake manifold but have been unable to find a build thread. Does anyone know who did this? I am wanting to do the same thing but don't want to repeat the same mistakes if there have already been some lessons learned. The car is an 87 GT, 5spd, with a 3.4L swap. It is for ChumpCar racing only.

To answer the first question of why do this and not some other intake mod? My Team and I like the idea of adding the throttle body this way because it fits the spirit of the series. We plan on cutting a hole in the decklid and sticking a cone filter out through it.

Is this the one you are thinking of?


We ran across that at Run For The Hills 14. It belonged to a local...unless I have things confused (which isn't all that unlikely), it would be Ken Wheeler, owner of Wheeler's Performance. I don't believe he frequents the forums, so I would be surprised to find a build thread.

Edit to add: I do remember that it was set up to only open the second throttle body at the end of the pedal travel....for normal driving, only the original throttle body would open.

[This message has been edited by CowsPatoot (edited 10-03-2012).]

Thanks for the info! It sounds like the same thing we are thinking of; to have it open only at near full throttle conditions.

quote Originally posted by Duck Hunter 117: ...modified to have a second intake on the top on the intake manifold

quote Originally posted by CowsPatoot: ...it was set up to only open the second throttle body at the end of the pedal travel....for normal driving, only the original throttle body would open.

Interesting concept!

Would it completely screw things up to add a one or two barrel carburator in that location to operate in the same manner (only functional when the gas pedal is floored) instead of another throttle body?

I'm wondering if adding the carburator would be superior (or easier for non-programming guys) than just using a second throttle body if in fact the stock injectors (and/or ECM programming) couldn't supply enough fuel at WOT with the added air flow.

It would be kind of a fun hybrid, if it worked. Seriously, I'm kind of intrigued by the idea.

[This message has been edited by Patrick (edited 10-03-2012).]

I havent seen this topic before , but last night I was just thinking about taking a stock intake , drillin 6 holes right above each intake port , tapping them and putting in some threaded pipe or adapters with breather filters on top of each as an alternative since I splurged and spent a ton getting a custom intake setup.

Be cool to make a custom intake where pipes intake tubes are symethrical to each other one of left and right of the car that run up to the sail windows with scoops fitment would be a pita , without a fastback.

I saw this thread a while ago and made a similar modification.
Mounted the TB on the upper manifold like the picture but eliminated the original location.
This was done to my race car (mild 2.8, cam, lifters, headers, etc).
The throttle response is better. Next item is to use a larger TB and see what happens.
I think if you drilled and tapped the manifold as suggested it would be a giant vacuum leak and not run.
That's why the original idea was to not have it open until WOT.

quote Originally posted by Patrick: Interesting concept! Would it completely screw things up to add a one or two barrel carburetor in that location to operate in the same manner (only functional when the gas pedal is floored) instead of another throttle body? I'm wondering if adding the carburetor would be superior (or easier for non-programming guys) than just using a second throttle body if in fact the stock injectors (and/or ECM programming) couldn't supply enough fuel at WOT with the added air flow. It would be kind of a fun hybrid, if it worked. Seriously, I'm kind of intrigued by the idea.

The stock injectors will support about 200hp if in good shape and if you are using the stock heads and middle/lower intake you won't get to over 200hp. I think your idea could work though, the only tricky thing would be setting up a low pressure fuel system to feed the carb. Talk to Dawg I am sure he could drill and tap a spare intake in about an hour. Hell I personally have the tools to do a TB mod onto an intake. Plus if you are running a TB and its setup to only open at WOT there would not need to be any programing changes, because when the ECM see's you go to WOT via the TPS it ignores the O2 sensors and just runs everything Wide Open. When I say everything I mean the fuel and timing maps. Which is why I was able to run 19# per hour injectors on a dry nitrous kit. At normal driving the ECM dialed back the injectors enough to run fine, and when I hit WOT it would dump all the fuel that the injectors could supply. Which would flood a non nitrous 2.8 below 3000rpms, but add the extra Air and it screamed to 7000.

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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

quote Originally posted by Capt Fiero: I think your idea could work though, the only tricky thing would be setting up a low pressure fuel system to feed the carb.

Perhaps a second fuel regulator on the fuel return line (off the injector rail) to feed the carb?

quote Originally posted by Capt Fiero: ...if you are running a TB and its setup to only open at WOT there would not need to be any programing changes, because when the ECM see's you go to WOT via the TPS it ignores the O2 sensors and just runs everything Wide Open. When I say everything I mean the fuel and timing maps.

Dave, I know nothing about ECM programming and what the injectors can and cannot deliver (and it'll be awhile before I have the '86 GT I'm working on ready to experiment with), but what do you make of this post in The thread I previously linked to in light of what you've just stated...

quote Originally posted by Pyrthian: you will of course need a custom chip made. especially if you plan the "secondaries" type setup. the fuel delivery is based on a straight curve for the throttle, and it takes into account the restrictions of the stock system by really cutting down on the fuel in the upper R's

[This message has been edited by Patrick (edited 10-03-2012).]

yep , that is mine. I have been driving it daily for over 2 years and put over 10,000 miles on it. I never had a chip made and the only other change was to up the fuel pressure a little. No dyno, nothing documented, just put it on and ran it! It gives it a real kick above 4,000 but adds nothing down below. I still get 20 mpg around town and hwy is 28 plus.Some will say it won't work but it does! I did drill a hole in my deck lid and have an old school chrome filter sitting on top.
wheelie

true that does make sense I did not think about that , It was a I cant stop thinking to fall asleep idea. But definitely looks like a good idea with the throttle body on top.

Instead of doing all of that, just put on a carb setup get more power and call it done.

Edit to add: I do not mean a carb on the stock intake, I mean a real carb setup.

[This message has been edited by sardonyx247 (edited 10-03-2012).]

If it were me, I'd block off the original throttle body location and put a TPI V8 throttle body on top. Just an idea.

With that setup and no air filter, you know that engine won't last long. Also with air intake of high underhood temps, power will be reduced.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

I'm guessing you missed the part where the OP said he planned to cut a hole in the decklid and use a cone filter?

quote Originally posted by Dennis LaGrua: With that setup and no air filter, you know that engine won't last long. Also with air intake of high underhood temps, power will be reduced.

quote Originally posted by Blacktree: I'm guessing you missed the part where the OP said he planned to cut a hole in the decklid and use a cone filter?

And I'm guessing you both missed the following comment.

quote Originally posted by WHEELIE: I did drill a hole in my deck lid and have an old school chrome filter sitting on top.

When I took the pic Greg posted, I also took several of the setup Ken had. Unfortunately, old files are no longer readable on a new computer and upgraded software. I think his method of using mechanical (cable) actuation gives more versatility as to when you want the secondary to open. It could run full time, at 1/4 throttle, or just WOT. Double manifold dual throttle bodies run full time, so why wouldn't Ken's system work in the same manner?

Combine Ken's setup with a 7730 and DIS and you may find some extra ponies in the back stall of the barn.

Man now after seeing this i want to run a cross-fire set up on my duke LOL. i know it should work and it would look cool as hell. since i have 2 parts cars both with dukes i can fab up a duel tb set up just to try it