refresh951

I am wondering if anyone has measured turbine inlet pressure (TIP) and has any data they can share? Having a curve that compares TIP to boost pressure would be extremely valuable as minimizing the ratio would keep exhaust gases out of the combustion chamber during valve overlap and therefore improve volumetric efficiency. I am going to look at finding a way to add TIP to my data logger but would like to get an idea of the pressure levels.

Anyone have any data they can share?

V2Rocket

Clicked on this hoping to see a compound turbo setup...multiplication FTW

You are looking for a sweet spot of exhaust pressure to balance spool (pressure difference across turbo sides) with VE? Time to call FRF for a VGT setup

TurboTommy

I've measured this and I'm seeing ratios of 1.1 mid-range, climbing to 1.4 at higher RPMs, 19-20 psi boost. It's slightly worse if ambient temps are on the high side.
Rennlist member Thom is getting similar numbers, I believe, but I'll let him verify this.
These are very good ratios, and is not the norm, but we were **** about achieving this.
Before that, I had a setup that crept up to a ratio of close to 2 at high RPMs, with still good performance.
Quite while ago I measured a bone stock non-S at about 2.5 at peak power; but I can't verify 100% the validity of that reading because I wasn't sure if the gas pressure to the gauge was perfectly sealed.

Tom M'Guinn

Couple of old threads might be of interest...
https://rennlist.com/forums/944-turb...-pressure.html

https://rennlist.com/forums/944-turb...pressures.html

Thom

I see 20psi of TIP for 18psi of boost, climbing to 22psi of TIP past 6k RPM.

My turbine flows 23 lbs/min while yours Shawn flows 27, so your readings should be at least as good, for the same level of boost.

When applying full load in 3rd gear at 2000rpm I see 15psi of boost no sooner than ~3500rpm, and given the very good level of TIP I'm seeing I have been considering trying a one size smaller turbine housing (flowing 21 lbs/min) in order to improve spool. However the engine feels so good in its current configuration that it's really far from being a priority.

refresh951

Thanks for the info. Exactly what I was looking for. Read in your old thread (thanks Tom M) that you installed a kit on the crossover. Can you give me some details of the setup? Sensor you used? Also, what turbo are you running currently? TIA

refresh951

Thanks Tom! I should have done a better search.

haha...not yet

Thanks Thom. As always, appreciate you input.

TurboTommy

No special sensor.
Drill a hole in the crossover. Weld a bung. Use appropriate crush fitting with copper tubing (I think it's 1/8"). Run the copper tubing up through the firewall to a boost gauge. I used a diesel boost gauge 'caus it will read up to like 50 psi. I've got my gauge in the glove compartment, just to check it once in awhile.
Because the gas is stagnant in the copper tubing , it will create pressure without there being any flow , so the gauge will never be subjected to any exhaust heat.
Tips: the open end of the copper tubing which goes to the cross-over should not stick so far in as to be flush with the main exhaust gas flow to the turbine. This open end should be away from the pipe a bit. The bung sort of creates this space anyway. And make sure there is a good seal at the cross-over; this is a hostile environment with easily occuring cracks and leaks .
When running the copper line make sure it doesn't touch or rub against anything on its' way to the firewall.
All sounds like basic common sense stuff, but if not done, it will be headachs

LR has a kit

Tom M'Guinn

Can't you just use the existing CO2 test port in the cross-over?

blown 944

When I was testing I used an o2 bung and drilled a plug out to fit the fitting. Then when finished I just installed a new o2 plug.

It's been awhile since I measured, but with the .58 hs(ptrim sizes hx40 wheel) I got it pretty close to 1:1.

Thom

I did that using the kit from Lindsey.

TurboTommy

I've got custom headers and cross-over.
Sorry, forgot to mention that part.

gruhsy

So to add some info. I have the LR kit installed and working now. My exhaust TIP was reading 7 psi at both 15 and 18psi boost pressure.
I have dump to atmosphere waste gate, 5 inch exhaust and a T4 exhaust housing...either .58a/r or .6/8. Dont remember which.

Thom

That sounds too good to be true.
At what rpm do you see peak boost when going full load in top gear?

TurboTommy

The fact that you have the same 7 psi exhaust pressure to both 15 and 18 psi boost, means there's something not right; goes against the laws of physics.
Where are you taking the exhaust pressure from?