How much boost?? and a few other queeries
Turbo Mini Forums

Now then, I am at a miss with myself as to what boost to run on the 16valver. Some help would be apreciated in helping me decide before i have the machining done on the pistons.

Let me run through the spec

MPi block running standard bore and steel sleaves, standard Metty turbo pistons and Total Seal gapless rings, Standard rods, new crank, four bolt center main and undercrown cooling. Oh and the BMW 16 valve head with 19.8cc chambers, looking at a dry deck using a standard Payen BK450 or AF460 gasket, depending on the maths of the CR.

I was hazzarding a guess at 15psi with up to 17 or 18 at the strip??? with a CR of 8.5. Going to use the TD05 intercooller i now have

Obviously going to use Megasquirt with a knock sensor, wideband lambda and pyrometer

I also have two turbos http://www.turbominis.co.uk/index.php?p=14&album=288 , and a little undecided as to which to use as I havent got a clue how many bananas this will push (got any ideas yet Jimster) theres an IHI RHF4 good for 177bhp and a 0.31 AR exhaust and an IHI RHB5 good for 208bhp and a 0.38AR exhaust http://www.rbracing-rsr.com/turbo/TurboMaps/IHI-chart6.gif and http://www.rbracing-rsr.com/turbo/TurboMaps/ihi_specs.gif (RHF5 iS the same spec as RHB5)

Oh and im not looking at reving the arse off it, it got to be road happy

Please help as things are happening very soon

MS

Edited by Sprocket on 16th Aug, 2006.

I think you need to be realistic here:

Boost = torque
More boost = More torque

More torque = Slipping clutch.

More Torque + grey diaphram + transmission stong enough to take torque = reliable (ish) fun.

MORE Torque + doublegrey + transmission stong enough to take torque = unpleasant clutch for a road car.



Basically - Decide what you want, and have done with it.

The EFI and 8-port will allow more torque for the same boost of an equivalent 5-porter; basically - I think you should be looking at 10/12psi for a start - and 15 on the strip.

Well that that sorted then

10psi base with the option of up to 15 for odd ocasions.

Thanks mate

Just need to decide on the turbo. Ah bollox, I'll make up a manifold and adapter plates so i can try both without too much trouble.

you forgot dave left leg will be fatter than the right with double grey

always looking for them bigger bunches of bannanas

ms something to bear in mind ,the spec sheets for the rhb 5 and 4 your showing cover a range of compressors under each suffix ,you need to find out which one you have to see if its got that 177 or 208 airflow ,or if its one of the smaller 4's or 5 's .
regards robert.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM