Oddjob

I just got a copy of some original info that came with the US Escort (Turbo Cup) cars from PMNA back in '87

In a section on the engine, there is a note "the waste gate has been changed (stronger spring and 3mm spacer)".

Im not sure what the effect (need) of increasing the spring rate and using shims would be (why both?). Unless the factory changed the spring rate, and then realized that it did not increase the boost level as much as they wanted, so then added the shims as an afterthought(?).

Anyone know what the stock spring rate is for the waste gate diaphram?
I believe that the Escort cars were running at 14-15psi, and holding it close to redline. Any ideas on the WG spring rate needed to hold that?

I have heard of waste gates being rebuilt with higher rate springs, but not sure of any reliable sources or shops that are doing this right now. Any recommendations?

Thanks.

hosrom_951

Lindsey rebuild the stock wastegates with a modified diaphram and convert it to a dual port wastegate.

special tool

Hosrom - preaching the obvious is your long suit.

hosrom_951

No it ain't aromatics man

951TurboEuroSpec

Im interested in this as well, When i was in Auclkand New zealand i got a drive in a friends 951 that had his own modified wastegate installed, I think he said it was a 1bar tial spring installed and he also converted it into a dual port. IT held boost until redline running 15psi. He said it was pretty easy to to do.


Does anyone no how to D I Y. this modification..

Oddjob

Sorry, Im not looking for the Lindsey dual port WG, or a tial WG, etc. Just looking for info on the factory stock WG and any clues to the stiffer spring rate that the motorsports cars had or needed to hold the higher boost level (using the stock WG valve body).

I have a set of the "300bhp - 100 octane" Escort chips. They were used with a 3.0 bar FPR and the above mentioned modified waste gate. I am looking at trying to run/test this factory setup and am trying to get some ideas and recommendations on what spring I should try with the standard type waste gate.

I will likely contact and discuss the waste gate springs with Lindsey, since they do make the "Club Gate" version of their waste gate, which is advertised as a stock setup. They should know what the stock rate is and may be able to offer suggestions on a stiffer spring for the application. Just wanted to get some background info from here, before calling them.

Also, any good sources on the 3mm waste gate shims? I know Lindsey has a one piece plate, but I would be interested in the set of three 3mm machined washers.

jerome951

Jim,
When I bought my car it had the Weltmeister chip and wastegate shim. The shim allowed it to hold ~14psi to redline, though I'm not sure of the thickness of the shim (but from memory looked ~2-3mm).

You may be able to run just the shim and get the desired performance.

special tool

Jim - I was under a Rothman's car on a lift and I was studying the wastegate - There was nothing additional between the diaphragm housing and valve housing.
Is it possible that EITHER spring or shim mods were made, not necessarily both????

Oddjob

Jerome - thanks for the input on the boost level with shims. I dont really care to run more than 14psi at redline, so the shims may be enough(?) - but then again, see my note below about the KLR chip mapping.

Special - very possible on the shim and/or spring setup. This is a very gray area on the motorsport cars.

The US Escort cars came with 3 sets of chips for the '87 SCCA endurance series, claimed to be 250bhp (called "eco" chips - used for fuel economy during endurance races, probably very similar to the street turbo S chip), 275bhp (for sprint races, probably the standard Cup chip), and 300 bhp ("power" chips for qualifying). The 300 bhp chips needed the 3.0bar FPR and obvioulsly also needed some mods to the boost system to get that kind of power, which is where I came across the info in my first post about the spring and shims on the waste gate.

My guess is that the Canadian Rothmans cars did not originally have a modified boost system (waste gate or other) to run the standard turbo cup chips. But the Escort cars trying to beat 350-375bhp corvettes likley ran the 300 bhp chips the whole time. The Escort cars had a reputation of blowing head gaskets (but were also running in 6 - 24 hour endurance races), so Im sure they had their boost levels up.

To me, it would make more sense for the Escort cars to just use shims, since those could be easily added or removed when changing chips. If the spring was also stiffer, then the other chips (the 250 and 275) would have to have the KLR/Cycling valve map setup for the stiffer waste gate and would not work well with a stock WG - which may or may not be the case(?).

I have heard reference to a "Cup" waste gate on Rennlist a couple of times. Sebastian of Asarus mentioned that his French cup car was increased to 300bhp for the '90 series, and that the factory updated the cars with a new chip set, 3.0 bar FPR, and a modified waste gate (this sounds very similar to the '87 Escort cars). He was not sure what was done to the WG since his car had been returned to 250bhp (with a stock WG) after the series ended to be sold as a street car.

I also saw a post by Pete Fitzpatrick (owner of the Rothmans car in the Excellence article last year) that mentioned he had played with shims and then replaced his WG with a "Cup" or "Club Sport" part and it held higher boost. I assumed at the time that he was referring to a factory part, but it could have been an aftermarket WG(?).

But I have various part lists from German Turbo Cups, Canadian Turbo Cups, and US Escort cars, and there is no part number listed for a different WG. The only info I came across was in a letter from Porsche to PMNA where it talks about the Escort cars already should be fitted with a waste gate that has been modified.

I will also add this: I compared the Escort chips to APE stg II in my 89TS and using just the standard jetted banjo bolt, the APE chips held higher boost at higher rpm than the Escort chips. The Escort chips really dropped off at high rpm - so that would tend to support that the Escort KLR is mapped for a stiffer WG setup, correct?

Looks like I will have to get myself a quality A/F gage and start doing some testing with shims and see what that gets me.

Again, thanks for any and all ideas, data, and experience.

Jim

Tomas L

I have tested different shims in my stock wg before I switched to a Tial.
IIRC the final shim I used was 8 mm, it may even a little thicker. With this shim and a custom KLR chip i could hold 1 bar to the redline. With this setup the difference compared to the Tial with a 0.8 bar spring was small.

Luis de Prat

Jim,

I think the person who can help you is Konstantin, a frequent poster on the 951 forum.

IIRC he rebuilds the stock wastegate using the "stiffer" spring from the 968 Turbo.