Equal length turbo header

[Clonebug]

You have a build page on that setup???

[petew]

Ok sidemarkers, that's really interesting. Just to be clear, it's not that I don't believe what you're saying about excessive back-pressure in #4. What I am wondering though is if there's something else funky going on with that cyl. So on a type 1, cyl #3 is famous for running hotter than the rest. This is why Mario encourages us to run the temp sensor on #3 for warm up. What I'm wondering is whether the aero of the squareback does something weird with the air coming out of the motor? Alternatively, could it be that turbo is radiating heat onto #4's cooling fins?

P.s. I'd love to see some pics of your car and setup. I have a think for squarebacks.

[sidemarkers]

Other than my 1966 work van in my avatar, the squareback has been my only vehicle since 1993. The life of a daily driver is a fairly constant routine of repair/upgrades. Last month I replaced a rear disc rotor which led to replacing my spring plate bushings and swapping out my stock spring plates for some 3 inch atomwerk drop plates.

[Piledriver]

T1 doghouse cooling in a square?
Must be noisy, but I'm a huge fan of my 73.

EDIT
Looks like you are running a draw through... The most likely thing killing #4 is lack of uniform AFR between cylinders//fuel distribution, which really should be expected to some extent with that setup.

With certain ignition systems you could put a crutch on it by retarding #4, or just running everything super rich with what you have for safety.

[sidemarkers]

T1 doghouse cooling in a square?
Must be noisy, but I'm a huge fan of my 73.

EDIT
Looks like you are running a draw through... The most likely thing killing #4 is lack of uniform AFR between cylinders//fuel distribution, which really should be expected to some extent with that setup.

With certain ignition systems you could put a crutch on it by retarding #4, or just running everything super rich with what you have for safety.

I am running a modified type 3 engine lid, YES that would be very loud without it!

Been running SDS engine management since the early 2000s, blow through intercooled, injected with crank trigger. Last time I dabbled with draw through carbureted turbos was early 90s.

[Piledriver]

I must have been looking at the wrong photo then, looked like a Holley feeding a turbo.
(it was bugguys setup)

As sequential fuel isn't happening, what are you using for ignition?
A slightly larger injector on #4 might be an option, as would a ignition that allows per cylinder retard.

[sidemarkers]

Ignition is handled by the distributerless SDS crank trigger and GM style coil packs. I'm using the 2003 version. Maybe I am nitpicking a bit too much. I just went for a ride to Sprout's to pick up some produce and peaked out at 19.5 lbs of boost.

[petew]

Love to see some pics of the engine and turbo setups. What size motor is it?

[buguy]

That's a ton of boost! Wish I could pull that off!

[sidemarkers]

It's a pretty basic 2276, minus some lightweight reciprocating components like titanium retainers, aircooled.net aluminum dual tapered pushrods and CB lightweight wristpins. Found a great deal on these rebuilt ported 42/37.5 heads with 3/4 plugs recently, big improvement from my worn out 40/35 heads.

[buguy]

Maybe I missed it, but have you ever had it on a dyno?

[sidemarkers]

I haven't dyno'd it yet. Which is almost funny since I drive it daily. I have been more concerned with driveability and broad RPM aspects than peak power. I really don't have any excuse though I should probably dyno it.

[buguy]

Yeah I suppose it makes what it makes either way. Might just be fun to know!

[sidemarkers]

Just posted more info and pics of car. Merry Christmas 2017!
viewtopic.php?f=3&t=150264

[seabeebuggy]

To me, I don't understand how you can have scavenging when you have back pressure. Add a turbo to spin at the end it really changes things. sounds like tuning.