Thread: Mild L67 project

Putting together a 97 GTP. Looking forward to breaking it in and getting the tune cranked up. I'll post up progress and results. Car supposedly made 210whp with only a CAI.

the-wizard-albums-gtp-picture10179-downsized-1121120944.jpg


New parts so far:

New GM longblock
Freshly rebuilt 4T65E
NGK TR6 plugs
Wix oil and fuel filters
160*F therm


ZZP goodies:

Short Stack HE setup
Stainless headers w/EGR delete
Ported lower intake manifold
Ported M90 with 3.25" pulley
Stg.1 TB






Feel free to leave comments and suggestions.

What are you using to tune with?

Got a wideband?

I would start with a 3.4 first, then pulley down once its safe.

Stock injectors?

my guess is #43

You might be alright.

From what I see, 42.5 are not a good option to go with because of the lack of data for them.

Thanks for the sugguestions guys. I like using the Siemens Deka injectors, but we'll go down that road once the motor is broken in.

I am surprised to see the injectors were scaled at 38# in the stock tunefile, and that the PE AFR was so lean at 12.4:1.

Also adding a small external trans cooler.

I already realize I should have used a stock Bonne HE pump; this damned Flowjet thing is big, heavy, and loud.

97 was the only year to have them at 38. Look at any 98+ file and you'll see its around 32-33 IIRC.

In reality its not, GM got cheap on the wiring and we can have an issue of of running lean after a certain amount of time at WOT. Thats why a fuel pump rewire is a standard mod and then change the table back to 38.

PE AFR is at 12.4 because of the adders, look at the add vs rpm and those tables, if you add it up its somewhere around 11ish AFR.

Thats why most people will zero out those tables and set a new commanded AFR all the time.

I think its 15. Havent looked in a while.

Originally Posted by Fivefingerdeathpunch

You might be alright.

From what I see, 42.5 are not a good option to go with because of the lack of data for them.

What do you mean by lack of data? When you do the math for fuel injectors in our cars they are good up to 400 flywheel horsepower at 80% injector duty cycle. Is my math incorrect?

I looked again and the timing is down to ten degrees of advance, but only in the last three columns of the high octane table. It's five in the low octane one! The AFR is not modified in the multipliers.....somebody may have been in here before.

http://www.rceng.com/technical.aspx?...8uf35rjVAai9dF

This is the calculator I use. For a .6 BSFC and 80% max duty cycle the 42s look good to about 350bhp. I don't know what to expect out of this thing, and ideally would like new injectors and a methanol setup, but I'll play it by ear for now.

Keep in mind when looking at the main table that there are adder/subtraction tables as well.

Personally that 160F sounds a bit cold for the mods you have. I'd add a future flow mod, say a cam.

The car is not mine or I would have gone with a thicker cooler plate, cam, ported heads, rockers, and likely a methanol setup. I'll look at the tables again, but didn't see anything that would modify the AFR in normal operation other than IAT or ECT.