9 replies to this topic

[foster]

Hey guys, Im curently thinking up how my new engine is going to work, and having no experiance with forced induction im in need of a little help!

Firstly my engine is 1420cc or something like that, a 1380 with an 84mm stroked crank, S rods, Omega pistons etc, good porting on the head with standard valve sizes, running a 286 cam as thats what i have spare and with standard rockers.

So the plan is to make up a blow through supercharged system as my brother donated me his eaton m45. A few things i dont yet understand are:

Carburation, i now realise i need a 'turbo' Hiff44 after buying an hs 6 already! But looking at turbo systems (are they similar?) they use a plenum chamber, what does this actually do and do i need to make one? If so ant suggestions?

Secondly whats the story with a fuel regulators, i have a facet red top and a filter king in the garage but do I need to use a high pressure pump and a rising rate regulator instead?

Any light on this would be great, cheers Chris

[Prawn]

From what I've learnt over a few days worth of research, you basicly need a full turbo fuelling setup with a blow through charger. The plenum chamber is basicly where the boost is fed into the back of the carb. it is needed, as not only does the plenum form a simple route of getting charged air into the carb, but also, holes in the plenum line up with holes in the turbo HIF body which presurise the float bowl I believe.

You will need a rising rate FRP, which also happens to connect to the plenum, as well as a high pressure pump.

Have you looked into what compression ratio you need to run?

[Turbo Phil]

Getting the compression down to a suitable level for forced induction use is going to be your biggest problem, with such a large displacement motor.

[foster]

First of all thanks for your help lads,

Cool,i thought that would be the case. So this plenum chamber, is there any particalar shape that it must be? With it being charged air do you have to worry about the way it flows? I rekon the standard metro one doesnt look "too" fancy. Also does anyone know if the size maters? I read somewhere that it should be 1.2 to 1.4 times the size of the engine.

As for the compression, ive got it down to between 8.1 and 8.4 i cant remember exactly as ive lost my bit of paper! I've managed to find a pretty thick decompression plate to bring it down untill i find somewhere to do some chamber work at a reasonable price. Im hope it will do the trick the but im unsure of how much boost i will be able to run safely, and for that matter how to measure it yet!

So if the red top facet pump isnt going to work, could anyone recomend a suitable pump for me?

[Turbo Phil]

I wouldn't worry about the volume to much, Leyland didn't follow the rules of 1.4 times the engine size & it's not a problem. What is important is the restrictor ring located inside it, this is essential.
Most EFI pumps are suitable, as is the Metro Turbo, Renault 5/19 etc

Phil.

[Prawn]

what's the restrictor ring for Phill? I noticed it looking through pics, and couldn't figure out the reason for it....

[Wil_h]

The restrictor ring basically drops the air pressure in the carb by 3psi and pressurises the float bowl at the plenum pressure.

This basically means that the fuel pressure is always 3psi abouve boost pressure.

[Prawn]

interesting! does that mean that when you say you're running 10psi boost, which is of course measured from a take off on the inlet manifold, the actual pressure within the IC and pipework will be 13psi? reduced to 10 as it goes into the engine?

On a blow through supercharged engine with an M45 then, you'd be looking at inlet temperatures created by an eaton at 13psi when you're running just 10psi of boost.

That's very interesting indeed

[foster]

Sweet, i rekon im just gonna try find a metro plenum, i wouldnt want to screw my fuel pressure up. Reet then, im on it!

[Turbo Phil]

I have a plenum in stock if you need one.

Phil.