North American Turbocoupe Organization

Can injectors be too big?
I've been looking at what most of you guys have for injectors. I see that glenn for example, has 42lb injectors (don't know if they're on the car yet). I'm not asking if these are too big for his car, but would they be too big for a TC with a 255lph pump, adj. FPR and a gillis valve set at 18psi?

What are on our cars from the factory?

Pete D Offline
The later TCs came with the brown top injectors rated around 36 lb, earlier ones had 30 lb injectors. Size needed is more dependent on the HP the engine is producing.
I've seen a range of from 260 to over 300 HP
as being what the 36s will support. I tend to think it's more toward the high side of that range, assuming you have an upgraded fuel pump and adj FPR to go with it. The other catch is you need the right EEC to support 36s. If and when you step up to 42s or larger
you will also need some kind of aftermarket control system to either modify the EEC program or replace the EEC for fuel and timing fuctions. Otherwise you will find that the car is too rich under some/most conditions. I believe Glenn has experimented with the 42s and had some difficulties so he can tell you more. A stock IHI or T-3 is not going to need injectors bigger than the 36s

88 TC X 2, 86 SVO, Main TC with K&N, 3"DP to 2.5"duals through Dynamax, Ric valve at 17+ and disconnected KS.
Elite Bodega 16" chrome wheels. Autometer pod w/ A/F and Vac/boost gauges.140 mph Motorsports Speedo New engine: Total Seal rings and TRW pistons, ported and polished head w/ cc'd chambers,1.59"exhausts, SS valves, gutted upper, knife edged lower, A-230 cam, Race Engineering Adj Cam Sprocket, Crowlers, ARP head studs, and rod bolts. Walbro 255 HP pump and Kirban adj FPR, T-3. Centerforce II, KB subs and jack rails.

[This message has been edited by Pete D (edited 09-04-2001).]
Pete Dunham


Glenn 88TC Offline
Posting Freak
I have tried the 42's and have gone back to the stock 35's. The eec can't control the 42's correctly. It pulses them like they were 35's. The eec constantly pulses the 42's like they were 35's. Then it realizes the car is too rich and backs off the fuel. It never catches up. If you must run the 42's you will need either a custon burned chip or an eec tuner. Either will force the computer to control any size injector you choose. You can go too big. I have the 35's like I said ealier. I just last weekend installed an adjustable fuel regulator for the first time. I am now in the process of trying to find an adeqaute fuel pressure. Right now it is set at 46psi and I have been running 24psi of boost on 94 octane with no detonation. I will be running the 35's until I get the BIG turbo or the DFI system. If I put in bigger injectors later I will probably move up to 55's. I will(read better!!) be making over 300 rwhp next spring and will still have the factory injectors in the car. I think I still have a lot of power to get out of this car before I need bigger injectors. Get the 255 high pressure in tank pump and an adjustable fuel regulator and it should be good for many mods. It should be good for more power than most people will try to get from these cars.

Glenn 88TC
current mods (14.096 at 97.29mph): ported & polished big valve head(1.89/1.59), ranger roller, gutted upper and ported lower intakes, t3/t4 turbo, MSD 6al, MSD Launch Control, K&N filter, Walboro 255 pump, Kirban adj. fuel reg., ATR header, full 3" exhaust with Dynomax Ultraflow muffler, Star stage III ceramic clutch, Tiny Avenger bleed valve

Mods in progress (have, just not on yet): 65mm throttle body, 42lb. injectors, Taylor pro wires, 4.10 gears, Spearco intercooler, Nitrous system
NO TC and NO headaches.

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