Maxed Out Injectors - Possible To Swap ?

[Sydneykid]

Since the discussion seems to be revolving around my rule of thumb and my experiences in drivetrain losses, I thought I might jump in here.

444 cc = 444 bhp, that includes allowing for acceleration and cold running enrichment (the 80% you commonly hear people refer to).

So you don't multiply 444 by 80%, my rule of thumb already allows for that, it's 444 cc's and 444 bhp.

Drive train losses, I have had enough engines on engine dynos and chassis dynos to know how much drive train losses to allow for. That inlcudes 2wd Skylines, 4wd Skylines, V8 Supercars, F4000's etc etc. All I can do is tell you what I have seen with my own eyes. It's been around 7 years since we had the same RB on the engine dyno and then on the chassis dyno, but it was the 4th one that year, and the results were consistent. The 2wd's lost around 55kw and the 4wd's around 75 kw. That result was very consistent from 475 bhp (on the engine dyno) to 660 bhp (on the engine dyno). Which interestingly disproved the % method of calculating drive train losses, which I never subscribed to anyway.

Some further background, that was pre Shoot Out mode Dyno Dynamics. But we have always used the same calibration methodology over the 4 DD roller dynos we have used in the 7 years and the same operator. The cars that we have had for that period of time show very consistent power outputs, so I am confident that the chasis dyno numbers are repeatable.

Moving on to the topic at hand. The 307 4wkw seems a bit high for 444 cc injectors, they tend to run out around 280 4wkw at 12 to 1 A/F ratios and 265 4wkw at the often used (so called "safe") 11.5 to 1. A 27 4wkw (7%) happy dyno is a bit unusual unless some inlet air temp or other cheating was going on. Maybe it's a 12.25 to 1 A/F ratio tune, or the fuel pressure is 41 psi instead of 38 psi, maybe a combination of all of those. Slightly happy dyno, inlet air temp creap, tiny bit up fuel pressure, slightly lean A/F ratios.

Now 550 cc injectors, I have used that size many times and with standard fuel pressure they are usually over 565 cc's. The 307 4wkw is a bit low for them, I have regularly seen 350 4wkw at standard (38 psi) fuel pressure. We usually run around 42 psi and 380 4wkw is the go then, which is a bit over 400 rwkw in 2wd.

The bottom line, my guess, if it was 307 4wkw on our dyno, would be that it has 500 cc rated injectors.

Cheers

Gary

[Gtrgodzilla67]

TRy getting them cleaned !!!!! and flow tested LOL

[SAM-32R]

woh... thanks guys lols..

didnt think it would get like this.. just wanted to noe if i could just simply

install new injectors.. but yea.. thanks for all ur words.. sepcially

sydneykid.. u've all been helpful.. i shall make my decision soon on wat to do

and will keep everyone posted on wat's happening with it.

thanks again