Just a thought on stock airbox modding...

[owequitit]

Modern carburetors atomize fuel better than port-injection EFI systems. Bisi proved this notion, although it's possible to get similar results by using shower-head injectors placed far down the intake tract.

Our Honda's benefit from warmer air on start-up since it helps with atomization(there are coolant lines running to the intake manifold), and the idle control devices(FITV and IACV) are heated too.

It is a little more complicated than that. Bisi was using them for a very specific purpose. He is now using fuel injection. There was a way to do what he needed to do, and get the finite control that fuel injection allows, and carbs don't.

[K2e2vin]

I agree, from an atomization standpoint, they work very well. They do have their limitations though(mainly controlling tip in and part-throttle situations). Just arguing about atomization For drag racing, where the engine just sees a small part of the RPM band and is at WOT most of the time, it works well.

What caused Bisi to switch was he couldn't get the carbs to run rich enough with methanol.

[owequitit]

I agree, from an atomization standpoint, they work very well. They do have their limitations though(mainly controlling tip in and part-throttle situations). Just arguing about atomization For drag racing, where the engine just sees a small part of the RPM band and is at WOT most of the time, it works well.

What caused Bisi to switch was he couldn't get the carbs to run rich enough with methanol.

I am pretty sure he was also able to make the switch without losing much of the advantage that the carbs were giving him. They do it in F1 all the time, which is one of the main reasons they use FI in F1.

[K2e2vin]

Actually I believe he made more power, lol. With the carburetors, he was running much leaner than he wanted to. With the switch to EFI, he was able to correct the air/fuel ratio.

[owequitit]

Actually I believe he made more power, lol. With the carburetors, he was running much leaner than he wanted to. With the switch to EFI, he was able to correct the air/fuel ratio.

He once told me why carbs, and his EFI setup allowed him to retain most, if not all, of that.

I am sure the ability to fuel it additionally, and also to more precisely control the fueling procedure, was a help too.

[johnl]

I have no idea who Bisi may be, but it sounds like his carb application is fairly specific and involves high rpm and gas flow speeds(?), which assists atomisation. Also, having the carb jets a fair distance from the inlet valve (which is pretty typical in some degree compared to most injection set ups) will tend to improve atomisation in a fairly turbulent high flow / speed air stream as it gives the fuel droplets more time spent in the turbulent flow. Howeve, this also tends to cause problems with 'wetting' of the manifold walls at lower gas speeds / rpm (hence the common use of heated manifolds on most carby set ups).

Many racing injection systems have the injectors near the intake mouths (so close you can often see what looks like a 'cloud' of fuel spray in front of the intake mouth as the pulsations in the manifold push air / fuel back out before 'sucking' it back in), and this assists in atomisation in high flow / speed air in much the same way as having the carb jets near the front of the induction system (not including any larger OD piping or 'air box' before the inlet to each cylinder).

Most street injection set ups have the injector much closer to the inlet valve so that when the fuel hits the hot valve it atomises more effectively, which occurs in low or high flow air at high or low rpm (though at high rpm / gas speeds may not be as efficient in this respect as locating the injector further upsteam). This also lessens the problems associated with fuel 'wetting' the manifold walls at lower air flows / rpm and thus becoming 'unatomised'.

A number of things adversely or beneficially affect the degree of atomisation by the time the fuel enters the combustion chamber, and the affects may differ at different rpm, but as fuel leaves the metering orifice (jet or injector) it will always (in my understanding) be more finely atomised as it exits an injector than a jet.

[K2e2vin]

The carbs allow great fuel atomization when near the intake port. What I was arguing was carburetors are still excellent at emulsifying fuel and in a lot of cases can atomize fuel better than EFI setups.

The injectors distance has been resolved in many setups. To solve the wetting manifolds, a lot of EFI race cars utilize staged injection/standoff injection. Bisi is using this method, and on CBR bikes they use this also. I plan on using this method too, with the stock GSXR1000 injectors on the ITB's and shower-head injectors at the velocity stack. The GSXR1000 injectors are set up to spray at the throttle blade to help improve atomization (This is for a D15B for those wondering). F1 cars...well they just have a really high idle.

Bisi Ezerioha is one of the fastest All-Motor Honda guys. I believe his best was around 9.5x IIRC, but best in event was 9.6x. He pilots a F22A Honda Insight, which outputs in excess of 430whp(still 2.2l, that was with the carburetors. It's way more with the EFI in there IIRC). His old CRX with D15 output ~270whp with carburetors and ran around 10.7. The CRX was a street car and he had it as a daily driver(with carbs) for awhile.

[lokuputha]

I have no idea who Bisi may be,

More pics of the newer set up:

www.bisimoto.com

[Otto]

Oh wow @ dual injectors and ITBs, very nice, I hadn't seen his new setup yet. And has he always had that coil-on-plug setup? I recalled seeing the stock dist. and everything from much earlier pictures.

[K2e2vin]

I believe he switch to COP around the same time as when he switched to EFI. Just guessing though.

[10thcb7]

I know some think these things dont work, but im wondering if the same effect could be had by using a completely stock air tube air box and connecting it to those flat panel ram air intakes? *with the filters removed

[10thcb7]

i can get a hold of a intake tube and box from a h22 98 lude would that help?