Been on a rolling road day today, and the car was run with disappointing results.
Spec: T34.48, 55lb siemens, Pace cooler, 4x4 inlet plenum, bosch 044 fuel pump.
On motorway car pulls well, peak of 30psi, holding 25-26psi through most of the revs, not sure over 6,000 rpm though (need to check), wideband AFR gauge indicates approx 11.5-12 on boost.
Anyway was expecting bhp 340+ish
Results of runs 2 & 3: 290's clutch bhp, 270's bhp at wheels (average transmission loss = 17 bhp), 360's lb/ft torque.
I can't understand why if the car is holding boost (significantly more than a T3 can), how it is under 300bhp ? And why the bhp doesn't raise even slowly after the inital boost spike.


RR was at AwesomeGTI, cooling fan on for runs, other Saphs gave reasonable results for there spec.
My intercooler practically touches my radiator, but would be supprised if the heat sink from that caused the issue.

 

what was your charge air temperature

 

Unfortunately as it was just power runs, i don't have info on boost, afr or act of the run from the DD rollers.
I have all these gauges in the car but obviously couldn't see them.
On the open road they are all fine.

 

ACT is your biggest issue on rolling roads for power loss
all dyno runs should monitor afr and act imo particularly afr

 

What boost does a T34.48 typically hold up the rev range ?

 

it's not a boost related issue
you have enough of that
ACT is the most likely suspect
did you ask the RR operator for his opinion

 

Surely ACTs should have recovered by the third run? The car was stood for a while before the first run, fans kicked in twice I think, but the 3 runs we're fairly close together.

 

They were having some iisues picking up rpm signals, as some cars had wildly varying figures.
Also noticed the torque and hp curves cross before 5,000rpm, which isn't right from what i've read before.
No specific comments from the operator.

 

30 psi from a little t34 compressor generates a far greater pre cooler temperature than a might ttt38 compressor like yours running 30 psi

my money is on your act

 

Some RR graphs do not cross at 5252 rpm as they are on different scales.

If the rpm pick ups are not spot on you might as well ignore the results.

Good old dynos...

 

Think i'll go put a little more effort into heat protecting the silicone inlet hosing around the turbo and physically between the radiator and the intercooler.

I'm running an airbox with relective heat material on the side near the turbo.

 

The scales on the graphs are aligned and use bhp & lb ft so the power and torque curves should cross at 5252 rpm. Also 17 bhp transmission losses sounds low, even for two wheel drive.

 

That was why i mentioned the losses, i'd of expected 30hp ?

 

what was the problem with your run compared with some of the other cosworth that were run
fraser made the numbers so what problems were they having with yours to his
If you are happy with the on road power and performance stop worrying about the rr figures
and they should have been monitoring afr on every car and every run

 

nail on head there tony, opps second fuel pump relay has failed didnt realise and melted engine !

 

dynojet notoriously overread aswell.

 

it really does shock me the number of these RR shoot out run what you brung type days where they do not monitor AFR it is as simple as sticking the sampler up the exhaust
AFR and boost should be plotted along with your power
I also think they should measure ACT and plot that too considering it is the key to power on a turbo charged high boost car

 

I had a pace cooler on my t34.48, 803 spec and it was shocking, changed to a 70mm airtec and it completely changed. Also with the depth of that cooler you should be able to make some room between

 

scooby secretly books a run on the dynojet rollers too
might as well have the full set of graphs

 

lol

 

Here's mine same spec different cooler..

 

but slightly more boost mat

 

True mate.......

 

and different rollers

 

What boost pressure are peoples T34.48 turbos holding at the top end ??

 

Think mines 28psi mate.

 

Matt is in the Guinness book of records for the most boost on a 0.48
he is the .48 boosty boy King
I wonder if we could do him a billet t34 wheel hmmmm

 

i was at the point with my T34 in the end, i didnt need a wastegate

Billet wheel is a good idea!

 

Id like to try 40psi with a billet wheel....

 

with a 500 style cooler its best to have it as close to the rad aa poss so you dont get a low air on pressure to the rad as that can cause over heating issues

if the cooler and rad are back to back then you should get a high on air pressure all the way through

i think your problem is down to a shit old cooler
they have come on a little since the pace one
and what rad are you using

 

I did ask why they wasn't monitoring the AFR's & got told they don't need to I also asked a few people who had been there previously & they said they've never seen the use the AFR on there cars.

Dave, your car is quick...enjoy it. I would give AWESOME GTI a wide birth & find another Rolling Road to try & for the club to use.

 

better would be to have you intercooler spaced forward of your radiator but with both of them enclosed in a cowl so that the air has to pass through both

 

but in doing that you have a high on air pressure and the air flow slows right down as i passes through the cooler thus giving a low air on pressure to he rad

low air pressure on the rad can only result in 1 thing

hight water temps

think about it

the act will not heat up from the rad as both will be getting good high air pressure passing through giving good cooling
but if you have a shite cooler and rad your fucked from the start lol

 

Rad is a standard one and never had water temp problems.

I'm going to space the cooler forward even if it's only 5mm and use some draft excluder to seal them so air flow/pressure is maintained through both.

 

Mine peaks at 29/30 and holds 26 to about 6-6500 when I change whilst racing (to save the big bills lol)

steve

 

but the air pressure to the rad wont be maintained because the cooler has slowed it right down

think your problem is the quality of the cooler in the first place

what you need to do is back to back the cooler and rad and still fit some kind of air dam so the air on cant escape off the sides

 

Yes it will. Park in traffic and then put your hand on the intercooler bolted to a 90 Deg C radiator and tell me if its now hot. If it is then its on its way to becoming an interwarmer instead and its cooling efficiency will drop hugely.

A great place to try this is Santa Pod.

The air passing through an intercooler is NOT supposed to be trying to cool the intercooler down to ambient from 90C...

 

I've just over 5mm between mine and seems ok.

 

Any gap is fine, solid contact is not.

 

Cheers mate......