Hey all,

A mate has a Sierra Cosworth powered Dax Rush. Its running green injectors, T34 i think, bleed valve to increase boost and a Bajoo (???) Chip. I think its pushing out about 300hp. 17inch wheels on R888's in 205/45 i think.

Problem is we've just changed the diff as it was running out of puff at about 110mph/5500-6000 revs in 5th gear.
Unfortunately both Diffs are 3.62 LSD items.
So what we thought was the problem isnt!

Its now in FULL standard cossie spec, the Diff, the Box and the engine (Just a little more go)

Why is it dying at 110ish? Surely it should pull through to 140 with aerodynamics Dax quote it to 149mph!

Any ideas on why is not working? Seems quick everywhere else.
Any ideas much appreciated as we have run out!

If it's doing 6000rpm at 110 mph, then at 15o mph it would need to rev to over 8000rpm. Would that be OK?

What revs will it pull in the intermediate gears?

This is where we're lost.... its probably 5400-5500 at 110 (could be as low as 5000 tho as it does waggle) And the limiter i think sits around 7500 so that would tie in ok....

Shouldn't be using a bleed valve, you should have a -31 actuator set to give around 26/28psi of boost.Ahmed bayjoo (cossie tuning god) chip should give upto 350bhp, is it running a 3 bar map sensor, cos it should be.What gearbox is it running a type 9 or full fat t5?

What revs will it pull in intermediate gears? We need to know the answer.

Its running adjustable bleed from the cockpit. About 18PSI i think.
Not sure on the actuator. It has a 3 bar map sensor and its on a T5 rebuilt box on standard ratios.

Dont have int. Revs yet, when i get a chance ill ask!

[Edited on 17/5/08 by charlierevell]

This might sound a silly question but is it actually topping out at 110?

Does it feel to stop pulling as soon as it gets to 110 or is that just as high as you've seen the speedo get, is that speed confirmed.
Just thinking that the speedo magnets might be passing so fast thast it can't read properly maybe, or that it isin't reading accurately.

I always thought top speed was achieved in 4th gear or is that in the real old days.

Well using 4th doesnt seem to make a difference. Its like it get to 110 and hits a wall....
We confirmed both 50 and 70 with my 56 plate saab and that tied up. Its also been sent away to be calibrated exactly. Revs match up with the testing machine we used earlier too. So thats all ok.

Its on a -31 actuator by the way and on average runs 18psi....

The most obvious answer is usually the correct one i.e. it's not making anything like the BHP you think it is. My 2.0L (modified) Pinto will pull over 110MPH like a train...

[Edited on 17/5/08 by andyharding]

Is the fuel pump flow enough for the power output ?

i had i same set up in a westie is the actuator holding the the boost or is it dropping straight off did you set the boost bye shortning the actuator rod or on the amel valve

Has uprated pump and filters, seems to only be slow in 5th tho, 1st to 3rd seem ok, 3rd pulls like a train.
I think the rod was shortend, which is the right way??

This might sound really silly, but was the cause of a similar problem I had recently. Are there any breather pipes in the airflow at all? I had one sticking out of the bonnet, and regardless of what gear I was in, I couldn't accelerate past 65 mph as the air was pressurising the engine. Just a thought.

very odd!

My 200hp vauxhall XE locost will only stop accelerating when I do!!

Its certainly still pullng like a train at 130mph, just my head is also being blown off so I have to back off, must try using a helmet!!

PS is deffo not gearing, std cossie will pull 150mph on std gears

18psi isn't a great deal of boost for a t34 to be running at, would have thought for the kinda of set up you have you'd be looking more in the region of peaking around 24-26psi and tailing off to around the low 20's. as someone else has already said what map sensor are you using? if you're still on the standard 2 bar then it'll just give up and won't bother so you need a 3 bar. don't really understand the bleed valve for extra horse power, i always thought the point of a bleed valve was to do what it says on the tin and bleed off the boost thus you can control you're boost levels.

is it running smooth enough the rest of the time? does it run rough when it runs out of go? need to see what it revs to through the rest of the gears as it sounds a lot like there's something limiting the revs. what ecu are you running?

Thing is, it should see over 110mph even on 8psi boost!!

Even a 100hp bog std pinto westfield will achieve more than that!

Unfortunately, I'm struggling for constructive advice, as I need more information.

Seems plain to me that there is something seriously amiss with the engine, but I have no idea what.

Hey all, not thought about the breather idea!

Bleed valve is there to offer some adjustment.... It has an uprated actuator etc.

Its on a 3 bar map sensor and all the gubins for 330-350bhp.
Standard cossie ECU i think.

What about the oil breather that goes down and stick out the bottom of the floor, could that cause an issue? ?