UK Spec B with Supercharger

[Spec BSC]

Hey Richard,

What size pulley are you currently using? You're looking to change to a 56 mm pulley to gain more torque down low?

Cheers,
Al

Currently running the 58mm pulley, but the mapping was never finished due to engine failure.

[Spec BSC]

Oil and filter changed, 56mm pulley fitted all ready for Thursday.

[RX25SE]

Oil and filter changed, 56mm pulley fitted all ready for Thursday.

Good luck!

[Spec BSC]

Ok, just got back from the rolling road session. The good news is the car survived and performed faultlessly. So this is what we have.



It appears were missing a lot of boost, on the last engine with 58mm pulley at 7000rpm we made 7.5psi on the new engine with the 56mm pulley at 6800rpm we still only made 7psi!

So my question is how come we always seem to be limited to around 7psi, as far as I can tell there is no belt slippage as the graph is a straight line, same reasoning that there aren't any other leeks.

So what am I missing?

[jslayz]

Great result, fun to drive I'll bet!!

Were porting and or compression ratio change done?
Is exhaust dirrerent?

[Spec BSC]

Hi J, it is fun. No other changes were made to the engine during the rebuild, we simply can't find the extra boost were meant to find by using other pulley s. Quite annoying as i was looking to make 400hp with the inter cooler kit etc.

[jslayz]

Has your injector % increased?
Now intercooled after the compressor right?

So the air is compressed mechanically and then compressed thermally.
Volume of air at say 9psi out of the compressor then that volume of air is cooled (thermally compressed) so its pressure is decreased at this point which equates to lower boost readings.....well that is my theory and is correct IF your injector % has increased.

?

Otherwise you have a leak.

[Spec BSC]

Has your injector % increased?
Now intercooled after the compressor right?

So the air is compressed mechanically and then compressed thermally.
Volume of air at say 9psi out of the compressor then that volume of air is cooled (thermally compressed) so its pressure is decreased at this point which equates to lower boost readings.....well that is my theory and is correct IF your injector % has increased.

?

Otherwise you have a leak.

As far as I know no change in injector %.
I agree that the cooling of the air will lower the boost but it should be cooling air that is under higher pressure from using the smaller pulley..

The tuner and rr operator both agree there are no leaks from the system as we would hear a 5psi leak and also the fueling was spot on which would of been out if there was a leak.

I think the system is maxed out and can't deliver any more even with a smaller pulley (my opinion) but asking Raptor.

[Spec BSC]

Ok compare these two graphs. Both from different engines with different pulleys.

The one above was running the 58mm pulley and made 7.5psi at 7000rpm

This one was running the 56mm pulley and made 7psi at 6800rpm, the bhp figures are so close and are only the difference in final rpm.

So from these graphs it shows that running the smaller pulley made no difference in boost or performance, please tell me I'm wrong. One of the reasons for going for a forged bottom end was to be able to run at higher boost safely, seems like I'm not getting it.

[3rspecb]

Check your BOV. You mention you have/had blow by, maybe your BOV needs to be cleaned. It may also be leaking, I had 2 of them leak on me so I replaced with another type. Try tightening the top screw of the BOV a little.

[Spec BSC]

Planning on hunting for any leaks over the next week or so, you never know I might get lucky.

An owner in the uk got in touch and asked if I wanted to take a few items off his hands for the incredibly low price of $400aus so I thought I would oblige.

So I picked up the following items on Saturday.





So we have some Delta speed sill extensions, not sure about these, if I do go ahead and use them I may well wrap them in carbon film to match all the areas I have de-chromed on the car. Also might try the eyebrows with carbon film first before spraying body colour.



The double din adapter unit was the main prize although not in a hurry to get into the stereo stuff yet.

[bigBADbenny]

Great score!!! Your car deserves no less

[Brunsy3.0]

Looks great man. Hope you get your pressures sorted ans are happy at the end of the day. Side sills look good will tie in well with your front lip

[Spec BSC]

Starting to get really hacked off with the whole car thing. Not only do I have a smokey engine, covered in another thread, but the boost pressure is still to low.

Just to rub salt into the wound, went to Simply Jap car show last weekend. On the way home, WTF, for the whole trip home the car made upto 12psi it drove like a wild animal. Next day back to 7psi. Have tested the inlet tract for leaks, non found even blanked off the bov, again no difference.

Really pissed off now.

[ferret89]

Have you done a smoke test for leaks?