GSXR 1216 turbo & injector size

For discussing injector selection,manifold modifications, throttle bodies, fuel supply system design and construction, and FIdle valves and IACs.
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Mr Merkava
MegaSquirt Newbie
Posts: 2
Joined: Tue Dec 25, 2007 11:31 pm

GSXR 1216 turbo & injector size

Post by Mr Merkava »

Hi

Planning for MS and few questions still open:

I have this kind of setup:

- Suzuki GSXR -90 1216cc 16valve
- Mitsubishi heavy industries TD04HL-16T turbocharger
- 8,36:1 CR
- MSD 2225 fuelpump (162L@3bar and 107L@5bar)
- 4 x 42mm Honda Fireblade throttlebody (integrated add-on-air system for idle will work)
- Boostpressure 1,5bar
- Powertarget is approximately 270-310hp, and in future 400hp. (of course with different turbo :)

I'm thinking of buying 4pcs of 630cc injectors. I have no room or interest for double injectors, and the TB's came without the stock injectors.

Question: Is megasquirt's code and calculationspeed in such state, that with following setup there will not be any major problems in vacuum area before boost? Or should I buy smaller injectors? I would like to hear your opinions about the situation.

I think that I don't have to worry about any pollutiontest or anything like that.
Last edited by Mr Merkava on Thu Dec 27, 2007 11:44 am, edited 1 time in total.
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efahl
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Posts: 102
Joined: Mon Feb 16, 2004 3:15 pm
Location: San Clemente, California, USA
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Post by efahl »

The only numbers that really matter are peak HP and peak RPM. Obviously, as HP goes up, fuel requirements go up, but not so obviously as engine speed goes up, injector size must be scaled disproportionately larger to account for non-productive open and closing time.

Assume BSFC of 0.55, so to get 100 HP per injector, you need to flow 55 lb/hr. A 630 cc (60 lb) injector with 1.5 ms open/close time will only flow 52.5 lbs at 10000 RPM with 1 squirt per cycle because of the requirement to allow 1.5 ms/cycle for opening and closing. I've got a spreadsheet with this in it, http://www.not2fast.com/efi/EFI_Calcs.xls (see the "RPM vs Fuel" tab) so you can play with it a little. (This is the actual and correct basis for the "85% is max duty cycle" argument that the uninformed try to lay as a blanket on all situations; in the example above, the max DC is actually 87.5% and will be more or less depending on the peak RPM and OC time.)

I would not worry at all about using "too big" injectors.

Eric
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