Blow through vs Draw

[GARRICK.CLARK1]

Hi guys.
Just asking.
I have done my engine blow through, draw through, back to blow through.
I have it running blow through using dells and its running the best its ever done in terms of smoothness/easy to start/fuel econ/looks/etc
BUT, it had a ton more power with a more aggressive boost hit when it was draw through. It would rip tires when the torque hit and dig deep on the rear. Not anymore, its now got a soft hit which I don't like.
Just wondering how the 2 designs can be so different in terms of power while using the same Boost PSI.
I wont be changing back to draw ,just wanna no how to get the big hit back.

[madmike]

You'd think it's the same but it aint that's weird ,,check the spark plug gap? mine was blowing the spark out with a .34 gap

[Chip Birks]

Hi guys.
Just asking.
I have done my engine blow through, draw through, back to blow through.
I have it running blow through using dells and its running the best its ever done in terms of smoothness/easy to start/fuel econ/looks/etc
BUT, it had a ton more power with a more aggressive boost hit when it was draw through. It would rip tires when the torque hit and dig deep on the rear. Not anymore, its now got a soft hit which I don't like.
Just wondering how the 2 designs can be so different in terms of power while using the same Boost PSI.
I wont be changing back to draw ,just wanna no how to get the big hit back.

It's too bad you dont have back to back dyno figures to compare to. You could be making more overall now, it just comes on smoother. You might also be dealing with the higher intake temps with the blow through setup, which could lower overall output. Have you had either setup tuned professionally?

[GARRICK.CLARK1]

I can see the higher intake temps being higher than on draw.
I do have water nozzles plumbed into each intake runner. not working yet, not got round to it. touch wood its not pinging so that's a good thing.
Its true I've not Dyno'd it, there isn't anyone round my way id trust to do it. Its all seat of the pants tuning with the how scary its getting to drive as well.
I've upped the boost a bit and have a solid 1 bar showing on the gauge. I don't see 1 being a lot. 1.5 is were I wanna be.
I'm only doing small single changes at the moment as its not run this smooth/stable in a long time.

[nbuscemi]

How are you monitoring you AFRs? I can imagine the draw through design allows the fuel to absorb a lot more intake charge heat. Another question: Are you using a modulator ring on your blow through setup? Im no expert on carburetors (hence why I converted to fuel injection for my turbo setup) but I believe carbs work best then "sucked on" opposed to being "pushed on". I wouldn't be surprised if you're fuel trims are out of wack when under boost with the blow through set up which is why you draw through had a stronger "hit".

Here are the Modulator Rings I was referring to. They create a secondary low pressure area above the booster jet / Venturi when on boost.
https://www.cbperformance.com/product-p/7369.htm

-Nick-

[GARRICK.CLARK1]

Hi Nick , I do have the mod rings etc already , fueling isn't a problem Its got more than enough up top. I may have to go smaller on the mains as its at 10.5 WOT. I'm thinking carb/manifold heat isn't helping hence its about time I got the water/meth working properly.

[Chip Birks]

It will definitely make more power if it's not drowning in fuel.

[nbuscemi]

I agree, 10.5 is SUPER rich and will take a toll on power. I've got my 1600T set to about 12.5 :1 at 10 psi of boost at WOT and it pulls like a train (once the turbo spools up anyway)

-Nick-

[GARRICK.CLARK1]

true it is a bit rich. I'll look at that next.Mod rings and mains work together on a turbo engine.
The rings enable you to use a small main, that's why mine is only a 140.
I'll get some 130's next. Hopefully that will get me an 11.5-12 AFR ,and save me a bit of fuel.