Building a P90 head for supercharger service

[PMC raceengines]

I think your spot on with your thoughts Xnke boost will drop , and the engine will make more power with the port job and port size ,

it has every time i have done this , ... one thing most forget with supercharged engines is the exhaust , make shore its at least 3in and free flowing , keep up the good work

[Xnke]

It is a 2.5" exhaust, full mandrel bent and muffled. I am re-working the header to move the v-band clamp up, allowing me to swap to the 3" sidepipe. Header is a 6-2-1 equal length design, 1 5/8" primaries, 2.5 inch secondaries, total length from valve to final merge is 36".

[Tony D]

Yeah, you want 3" on it!

[Xnke]

The way I plan to do this is run the 2.5" full exhaust as my daily; and switch to a 3" pipe that dumps right in front of the passenger rear tire for the odd day at the track (they just broke ground on the new 3.2 mile road course!) and days I feel like being a dick on the highway.

 

The header was worked from the beginning to go from the 1 5/8" primaries into the 2.5" secondaries, cone down to 2.5" and then back up to 3" for the exhaust. I may build a full 3" pipe early next year; depending on funding and enjoyment factor.

 

Remember...this is my only car. I have to live with it every day, and part of the challenge is making it livable! This car will be built to handle 30 minute stop and go traffic jams in 100*F heat in Kentucky, as well as reasonably rowdy interstate driving at 70MPH in 20*F weather. Rain or shine, this car needs to behave. (That last bit is the reason I'm going to mount some rather ugly wheels on the car...Tire selection!)

[josh817]

I don't know what application it went on

 

40.5mm valve as a port guide

 

Good luck on the motor. I try to keep notes of all the things people advise to do but it's blowing my mind how many little things to remember.... Didn't even know about the LS1 valves. I bought an E88 head on here for $100 and it too has 38mm ports, shortened guides, etc. It can take bigger valves but I really don't want to mess a good thing up! When I spoke with Don Potters widow, she said the same thing Tony did, never really went past 36mm. I'm sure it will be great fun either way.

Edited June 12, 2013 by josh817

[Xnke]

For me, the port diameter is to lift the port up in the head. Theoretically I could push the port floor down about middle of the radius, then weld up the floor near the manifold face to lift the port, increase the short side radius, and retain the 35mm diameter, but that's a lot of work that just isn't necessary at this level.

 

Pending an agreement with my neighbors to not run the die grinder during their TV shows, I am not getting much work done during the week right now. (Please don't from 6 to 8, thanks!)

[didier]

compare to N42 stock and my P90 ported 40 mm intake and ported exhaust too. 

 

 

 

 

 

 

[Xnke]

Had a bit of mixed luck this afternoon!

 

I missed a buy of a 1976 Toyota RA22 Celica by fifteen minutes...the car sold for scrap metal to a dealer. I have called said dealer trying to throw money at him to get it before he crushes it.

 

BUT! I found a local flowbench and slapped the currently-37mm-ish ports on it, and did a little flow work! This is with what's left of the old valve job, on used, but clean, stock-sized valves. I lapped the valves in to get them to seal up closed, but that's about it. The top angle of the 3 angle job is still there, but a lot of the bottom angle isn't or is modified from the die grinder.

 

Lift - Intake Flow
.1 - 62.4
.2 - 117.1
.3 - 157.8
.4 - 199.1 (FIGJAM!)
.5 - 214.1

 

Lift - Exhaust flow
.1 -- 51.4
.2 -- 80.3
.3 -- 102.1
.4 -- 128.8
.5 -- 134.1

 

Not too bad! I have no idea how this compares to a stock port; as I don't have any heads with stock ports except a Maxima N47. I also have no idea if this bench is padded/accurate/garbage...it's an old garge-built unit that seemed pretty consistant, though. I was getting very close to the limits of the bench, I had the air valve wide open to get the full 28"WC for the upper end of the intake flow. A guy in the back of the neighborhood has it, but he's moving out this week. I saw it in his garage and asked if I could borrow it for a few minutes. An hour later, I was done and helped him load it into his moving truck.

 

I asked...he didn't want to sell. I have a very good idea of how to copy it though...

Edited June 14, 2013 by Xnke

[Tony D]

I had a 76 TA22 GT...it was possessed... Heart of a 73 GSS Corolla, 18RG-R with 143HP. Made all the right noises, just didn't go that fast (compared to the S30!)

[Xnke]

Yeah...this one was going to get a 1UZ-FE, ITB's and headers. Gloss black paint, full chrome, black leather interior with banana yellow inserts in the seats...

[Xnke]

Did some comparison datalogs today, thought I would update this thread. Originally, the same drive ratio with the old head produced 9.5lbs of boost from 2200rpm to 7000rpm. Wth the new head installed, datalogs show 5.75lbs of boost over the same range. Same cam, same intake runners, sane intercooler and pulley on the super.

 

Decent improvement in breathing, if you ask me!