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Is i allowed to use carbs AND injectors?

I don't believe you will get the power curve back the way you have ported the head and intake manifold, you have turned both ports in to something lazy. A somewhat lazy cam profile and not enough room to optimize the headers doesn't make it easier either.
If it was me then I would start over.
I would also focus on the bottom end to remove weight and friction, even a small amount gained there will make a somewhat big difference on an engine like this.
Building it more lika a VOC engine but with some touchups in the head that they can't do and a modern cam to complement should give you a good engine.

no cant use both carbs and injectors! lol

I was not sure what to do with the head, its a 531, so i was thinking to stick with it , and defo when ive done the manifold it sounds a lot smoother. I can hear its made a big change. But only will know when i take it the rolling road. If it dosnt work, then ill get a head done.

one problem i see atm, is my pipes on the exhaust are not equal lengths, may cause problems.

bmw2101 skrev:no cant use both carbs and injectors! lol

I was not sure what to do with the head, its a 531, so i was thinking to stick with it , and defo when ive done the manifold it sounds a lot smoother. I can hear its made a big change. But only will know when i take it the rolling road. If it dosnt work, then ill get a head done.

one problem i see atm, is my pipes on the exhaust are not equal lengths, may cause problems.

I cant see youre secondarys on The exhaust, but try to double The length of primaries. Put bends on then IF you need. Dont think that vill be a problem.

Rules, Can you run a special intake with a 2 barrel carb? And then there is no limit in butterfly area?

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yes i can run what ever i want with the carbs, just needs to barrels. I dont really want to go down that route, it is a lot easier to tune with the injection and im not sure i really need more than the lh2.4 atm? But i dont know its all guessing for me


the manifold




thanks for the reply!

i think Matti is at the same thoughts as myself, try to "cheat" them rules by using carbs but with injection as well!

The T5 cam is pretty good but you have a very low cranking pressure.
What is your compression ratio and do you have an adjustable cam wheel?
The F manifold will be your biggest restriction.

Erland

static compression ratio was 11:1 i think, the gasket is 0.65mm cometic, and the chambers are 41cc, adn the pistons dished 3cc.

the engine is b230a, t5 cam, 531 head i ported, standard valves, lh2.4 with 850 injectors, 63mm inlet, solid lifters, uprated springs, adjustable cam wheel, microsquirt ecu. so everything is adjustable, the restrictions for this engine is the inlet for injection, or i can use 2 barrels for carbs.

thankyou for the reply Erland!

On my racing engines that I run on 98 RON +Mon /2 I have a cranking pressure of 16+ bars.
I believe that you can use more than 12:1 compression with that cam as the intake will act as a restrictor.
I did a stock valve 405, same shapes as 531 and it flowed 205CFM at 12mm:s.
With the F intake it was down to 160CFM.
Flowing the F manifold ports showed 185 CFM so the plenum sucks.
This F manifold was ported at the injectors but the problem is in the plenum.

Erland

Erland, what do you think would happen if a tube was welded to the flange behind the throttle body that would reach say... 10mm in to the plenum, to get a clean edge for the air break free from?
I'm guessing part of the plenum problem is the rounded over entrance.

I don't think that it would help. But moving the entrance to the plenum 90 degrees would.
It is an expansion problem, air moving in to a big box without pressure recovery.
No walls helping the air enter and recover.
A long diffusor beteen throttle and plenum with a much larger entry into plenum would also help.
Putting on a larger throttle helps.
I have an F manifold cut apart waiting for me to try and fix it.

Erland

is there a way then of it lookign standard but being modified inside to work well? i ma really interested in this as the F manifold really unless i goto carbs is the only induction i can use.


also i kept saying lh2.4 earler on the thread, i thought that meant the F manifold, but it dosnt, means the ECU.

I am going to look at it but it will take a little while. Anything that slows air entering the plenum will help.
A bigger entrance, bigger butterfly, diffusor.
Or swapping the throttle to the short side of the plenum.

Erland

right ok, i cant have the throttle moved though!


should i take my head off and skim it more then to get moer compression?

thanks!

if i was to put carbs on this engine, would a pair of hs6 carbs be too small, as in Su 1 3/4? I can do this legally and there is no restrictions.

There is also the stromberg 175 which is simular.

thanks