GT40X fuel/tune requirements

[90LX5spd]

The price of GT40x heads has come down enough to tempt me into buying a pair for my basically stock '90 LX (with the exception of full exhaust). I'm a carb guy so I'm not sure what fuel system upgrades I'll need. Do I just need 24 lbs injectors and a matching MAF or is there some sort of tuning involved (adjusting fuel pressure or otherwise)? I replaced my pump awhile back and upgraded to a 110gph BBK unit. Is that enough? I'll want to run a Cobra intake, 65mm TB and my stock HO cam. The thing I like about the GT40x is they accept all the stock hardware like rockers and such (roller rockers aren't quite in the budget yet). I'm willing to sacrafice horsepower for a good reliable torquey street motor that will last a long time.

 

[f8tlfiveo]

You can use the stock injectors and mass air sensor.. You might want to upgrade mass air sensor to a 70 mm 94-95 gt unit.

 

[wythors]

If you're sticking with the stock cam, your stock fuel stuff will be fine. If you're going to increase the size of the throttle body, you'll want to upgrade the MAF as jeepguy suggested.

 

[90LX5spd]

Great! That saves me some money not having to spring for injectors. Should I just get a MAF calibrated for the the stock 19lbs injectors then? I take it that with the larger throttle body, the stock MAF becomes a bottleneck then?

 

[90LX5spd]

I forgot to add: I see the GT40x heads are available with 64 or 58 size chambers. Which do I want to select if I want to keep my compression ratio about the same as the E7s? Thanks.

 

[f8tlfiveo]

Get the 94-95 gt maf on eBay or a junkyard. It's calibrated for 19 lb injectors and it's alot cheaper. You have to get an adapter for it though. It has a flange on one side.. Unless you have access to some tools to make the adapter.. I made mine.. But I have a welder and access to machine shop equipment.