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Discussion Starter · #1 ·
Speedemon and I were talking recently about our new FMIC's (pics to come later) and what the best tuning would be to take advantage of them. Got us thinking about the capacity of the stock fuel injectors.

Blot- I see you have 750cc injectors from RC engineering. Do you know what size the stock ones are?

Johann- I think you mentioned that RICA had to limit boost one your car at one point due to near limit cycling of the stock injectors. Was that when you had the K24 or your new turbo, or both?

Is there any reason that different injectors would be needed with the stock turbo, limited at 21psi? When (at what rpm/boost) would the stock injectors reach their max duty cycle. Granted I want to leave in some margin for safety.

DE
 

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Re: R fuel injectors limits (DE V70R)

HP wise you can go over 400 on the stock injectors.

It is the load enrichment where you need to check with higher torque numbers but a KKK won't get you in that area.

With my setup midrange torque was at the lower side. 330 lb midrange, 310-302 between 6900 and 7200 RPM. Overall a fairly flat torque curve between 3500 and 7200 RPM.

A/F was 12 to 11 high with this setup, no indication of injectors maxed out. Normally when an A/F curve starts to move up and down a lot it indicates the injectors being at their max. Never saw that behavior.

750's are sort of by the book for a 450 engine HP setup .

With the Bosch injectors and the experience from other tuning projects it pretty much shows that CC's indicate absolute max theoretical power on a 5 cylinder... It appears as if the Bosch injectors have very good recovery times.

The R uses 465/475 CC injectors so basically these could provide enough fuel to produce a maximum of 465 engine HP. take 90% and 418 will be your safer maximum..

With my 850 using 350CC injectors it showed that they had a hard time keeping a steady 12 A/F when engine HP went up in to the 320-325 HP area. between 6500 and 7000 A/F shifted to 12.5 while ECU settings suggested 12. This more or less confirmed this calculation but injectors were stressed in this setup.

RC engineering and some other calculators base their ratings on a very low duty cycle apparently. I don't know how to calculate based on duty cycle but I think a DC 0f 60% is preferred. If on a 5 cylinder CC=max HP then you could say max HP x pref DC = CC


In other words, 450 BHP / 60% DC = 750 CC


Don't you love 5 cylinder!


Remark, these and HP numbers at the crank. Wheel numbers are useless..
 

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Re: R fuel injectors limits (Johann)

Super, so at this point we don't need to upgrade our injectors until/if we upgrade our turbos. Can't wait to get the rest of the parts for the FMIC and mount it and go to to RICA for a tune-up.

Johann, any late rumors of a soft-loader from RICA? I know of two US spec MY04 V70R's available for testing, hint, hint
!!!!!!!
 

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Re: R fuel injectors limits (speedemon)

Remote tuning is possible. No softloader.

Just come and visit the tulips when you are ready..
 

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Discussion Starter · #5 ·
Re: R fuel injectors limits (Johann)

Johann,

Thanks for the great input. As soon as we get everything installed. I am ready to come up there. The hardest part will keeping the throttle in check on the way home through Belgium.

Kelly, are you interested in going?

DE
 

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Re: R fuel injectors limits (DE V70R)

Quote, originally posted by DE V70R »
Kelly, are you interested in going?

Getting my knee sliced open Wednesday, so I don't think that is in the cards until March... can you go to another country on convalescent leave?
 

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Re: R fuel injectors limits (DE V70R)

I wanted to go 650cc only, but since MTE already had a 750cc program, and RC was selling the 750 at the same price as the 650, I went for it.

Why a higher cc injector?

Well, given our hot climate, when the H20 runs out, the next best thing is to use fuel to prevent detonation. Moreover, most injectors work best at 80% duty cycle any higher and you run the risk of them failing at the most unfortunate moments which may result in engine damage. With the stock injectors plus the mods and tuning, I will be running almost 90% injector duty cycle which imo, is not good in the long run. I also run my car on the track often and hence decided to go higher.

The disadvantages are a slightly rougher idling and a longer crank to get the engine started.

Btw, this link which was provided by JimLill, and which I've inputted what I believe to be the correct figures for the stock R shows an injector duty cycle of about 70% at 5300rpm...
http://not2fast.wryday.com/tur...le=70

with MTE's new rev limit of 7500rpm, and more power etc... 80% duty cycle is easily breached...
http://not2fast.wryday.com/tur...le=87

Modified by blot at 10:55 AM 1-30-2006
 

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Re: R fuel injectors limits (DE V70R)

Where did you get your FMIC's

Are there any other companies selling FMIC's for the R?

Thanks
 

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Discussion Starter · #9 ·
Re: R fuel injectors limits (Stoobey)

I had ordered and put in a deposit on the intercoolers from Svenske/Alamo when Richard first announced them last year. Brice and Kenny honored the order and have been patient with all my phone calls to get these intercoolers. The core is 21.5 x 9.0 x 3.0. It has a large internal flow area (cross section of internal passages), good end tank design, and inlet and outlets are both 2.5 inches. We also wanted something that utilized the stock over-engine pipe for the stock look. They shipped all the parts for the full installation kit, but the boxes with the cores arrived first. Drool, drool--waiting on the pipes.

DE
 
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