Engine spec help

[Dave_M]

Afternoon all,

I'm hoping someone can give me some advice around engine spec and driveability. My spec is as follows:

CR Turbos roller bearing T38
c. 8:1 compression ratio
Ported head
BD16 inlet cam, std exhaust cam
airtec rs500 intercooler
Auto Specialists inlet manifold
VTA dump valve (which is going to have to go!)
P8 management

This was mapped on an engine dyno and made 425bhp. The problem I have with it is that it's completely gutless until the boost comes in at c. 3,750 rpm after which it goes like stink. I chose a T38 as I'm still running the standard gearbox though I am using a 6 paddle clutch. I really don't like the way it drives compared to when it was running 380 bhp on the original T35 turbo - the combination of the on / off power delivery, the sharp clutch action and a notchy slow witted gearchange (quickshift) are driving me mad.

So suggestions please?

Does the way it drives sound right given the spec - I never had the map checked / tweaked after the engine was fitted to the car, so maybe this should be my first step?

Is this inherently the way a T38 delivers the power? If so I'm thinking I might need to bite the bullet and swap it - maybe for a BW 7064. I don't want more power, and would happily trade power for driveability.

Or is this a function of the different inlet cam and / or slightly reduced compression ratio? I believe standard CR was 8.5?

I realise I'm going to need to spend some money to get this sorted, and in an ideal world I'd do the BW turbo, new management and Oppliger gearbox - but I don't have the budget to do that . I'm sort of wishing I'd left it in the previous 380 bhp spec at the moment, but going back to that feels a huge backwards step given the spec of the engine (long studs, under piston oil squirters, ported head, sump baffle, wrc breather....).

Thanks
Dave

[Grand Tomismo]

Was similar to my old spec. Had BD14 inlet, BD10 exhaust cams, a 14mm plemun spacer and 2wd exhaust manifold

Mapped it on an L8 by Norris Motorsport and had 440bhp, 380 torque.

It lagged bad then came on strong as all T38's do. Fine as 4x4, a complete handful 2wd.

I did look into calming the boost curve and run less boost, but that then gave an even laggier response, aproching 5k revs for 10psi boost.

T34 is an easier, miles cheaper conversion if your not totally bothered with a power increase.

I have gone down the Borg Warner route, long stud etc as I want more driveable performance and added factor of reliability.

[mark shead]

The efr and manifold will be a massive change over what you have.

Mark

[manoj]

I think your Inlet Camshaft or cam timing could be the problem making it laggy, perhaps a AB07 Inlet and Standard Exh would be better suited to a CR Roller Bearing T38, ask others for advise - someone like Dave Pritchard or the person who mapped it.

As Mark says, if your budget allows a BW EFR Turbro and Twin Scroll Exhaust Manifold will be a massive step forward for responsiveness on spool, power and driveability.

[Davecos 4x4]

I had a t38 and it was like having a t4 did not think it was a good turbo and that was with standard cams.

to keep your power you may have to go the efr turbo route or less power and put your t35 back on and run it at max.

[Big_Al]

Why EFR? Go ordinary BW instead, cheaper and not bad at all compared to the EFR.

[Dave_M]

Thanks all - confirmed what I suspected..... need to decide what I do next!

Dave

[cossiedavid]

Like we said when I built it Dave the t38 will be laggy we could mess with the cam timing on the inlet and make it a bit better if you don't want the expense of the efr then try a t34 and see if it's any better depending on if you want to drop to 360/380bhp give me a call if you like and I'll talk you though it