Chaps,

What do you think? I'm thinking rising rate, as it'll allow for linear increases in injector opening times under boost, rather than increasing times for boost, and drop in fuel pressure.

Do you agree? Or not

Also, any suggestions on how to make a vac advance distributor function properly under boost; ie no vacuum.

Thanks

ATB

Simon

Rising rate is the one to go for,conected to your inlet plenum,Ive got a begi unit fitted,45psi fuel pressure on tickover,65psi on boost,your settings may not be the same,but turbo engines use rising rate regulators.

Personally for boosted engines I'd want the flexibility and control of a non-dizzy (ie EFI) setup....
Aren't rising rate regulators a way of avoiding further complications when adding a turbo to a stock setup? ie a way of getting round problems with the fuel metering?? I might be wrong though

Paul,

OK, next q. Where from and how much and alternative suggestions? I found the US site, but no UK suppiers, apart from an MX5 site.

Cheers

Simon

Fixed rate - this way your ECU has control of the fuelling as fuel delivered is proportional to injector opening time (always assuming your injectors are sized sufficiently). The only variables are then the ones YOU dial in when mapping.

bartonp,

Yeah, but as I'm turboing, does the effective pressure not decrease with boost ie without boost I'll get (say) an injector pressure of 45psi. Running 14psi boost my injector pressure will be reduced to 31psi, requiring longer injector openings (taking them closer to "always open", whereas rising rate reg will compensate for this, and I'll not need to extend injector open time.

Thoughts please

ATB

Simon

no no no no no!! (as in your thinking is right but you've missed a critical detail! )

You pipe the inlet manifold to the pressure pipe on the back of the regulator. All the decent ones have these, and on a N/A setup its just left open to atmosphere (or that's what I do anyway) but on a turbo setup it is piped to the inlet and exactly offsets the boost pressure, i.e. 50psi fuel plus 20psi boost will give you 70psi fuel measured on a guage on the line.


A rising rate reg will give you 1.7 times approx the press change i.e. it just complicates things.

Any pressure reg with a port that feeds pressure to the back of the diaphragm, that can work with your intended boost press plus your baseline fuel pressure will be fine.

FSE ones are common but not very reliable and can suffer fuel press fluctuations.

[Edited on 13/3/07 by NS Dev]

My understanging is exactly as ns dev says.1 lbs increase for 1 lb boost. The drag guys that use my lima engine run it that way and the factory runs it the exact same way. The common way is to use an adjustable regulater that is set to increase at a 1/1 to the boost level.
Dale