walden

I have a 79 3.4L that I just installed Imagine autos modified fuel head on. My question is on air fuel ratios. When I first start the car it is around 12 and after a few minutes it settles in at 12.5. At cruising speeds it is 14.5 to 14.7. Under full boost it drops to high 9s to 10. After driveing for awile it idles at 16 but is still 14.5 at cruise. Just wondering if anyone had any opinions about the numbers. I allso have an andial fuel enrichment kit that is turned down to the first notch. Thanks

On a side note under boost the car runs better than ever with the new fuel head.

JoeMag

takes about 10mins for wur to fully warm up, so it's not fully warmed up after few minutes. after you adj CO ya need to drive around for stint and then check again at idle. it'll change slightly.

senna21

It's my (possibly false) impression that with the Imagine fuel head mod you don't need that Andail fuel enrichment kit. They serve the same purpose with the Imagine being the better solution of the two.

Stephen, should he be running with the Andail along with your head mod?

nathanUK '81 930 G50

Turn off the andial and test for AFR again.

If the numbers you posted are accurate then it would seem you are running too rich on boost.This is what the andial was for, to enrich on boost.

NSXTC

All your numbers look off. At startup, it should be 12.5 then settle down to 14.5 idle. At cruise, it should be around 13.5. At boost, it should be 12.5.

Try what Nathan says...disconnect the Andial and see what you get.

Another way to get the numbers is to adjust the WUR. If yours is not adjustable, you can get it modified to be able to control cold startup/warmup/and boost pressure. All three can be tunned independently if the mod is done right. Contact Brian (leask@***.net) on the WUR mods.

If you think your fuel mod kicks A$$ now, just wait until you get your AFR dialed in. 8)

DonE

The fuel head mod by itself (while it helps) does not take the place of a fuel enrichment system. If you modify the WUR, you can eliminate any FE system. I modified mine to provide additional enrichment at 4 lbs of boost.

PorschePhD

You do not need the enrichment from an out side source with the head modification. Your on boost enrichment comes from the WUR. What we do is add enough flow to accommodate more fuel thus the stock enrichment is now enough through redline to supply enough fuel. On average we run an AFR at WOT at 6200 of 12.0-12.1 max. This is about a 420 RWHP configured car. No WUR adjustments, jus the fuel head with the proper AFR sets on the dyno.

Take the Andial unit off.

DonE

My 930 needed the WUR adjustment. It simply could not supply the fuel fast enough in the early rpm range, but held approx 12.0 AFR to red line. The best AFR I have seen on a CIS car is Brent's 930 where the AFR was nearly flat from about 3500, on. That was with a very well adjusted WUR and fuel head mod. We were both in the 410 to 420 rwhp range.

SGOGT4

Stephen -

My thinking on setting the AFR is this:

I have installed a wideband o2 sensor and gauge that mounts to the dash. Make several hard runs and monitor the AFR reading through the rev band. Adjust the mixture at idle such that when on boost it maxes at 12.1 AFR.

Good?

I know that your mixture at idle doesn't matter as much as on boost, and that different cars will run different mixtures at idle in order to ensure not running lean on boost, but generally speaking, if you want to maintain 12.1 at boost what would a car be expected to run at idle?

PorschePhD

Don,
We don't do the fuel heads like we originally did them. They have changed a bit since then. We are flowing more than we originally did. As I mentioned I do not need to change the WUR at all on our mod. 12.1 @ 420RWHP is where they all roll in at. Brent's system utilized the frequency valve to control the curve. His head with the valve in place would not flow like the other mod with just the head alone.

Rob,

Yes, that is good. 12.1 is perfect. I normally see the AFRs with a moded head somewhere in the mid 13 range. Again it will depend on the car but that is where most end up.

74carreraturbo

What are the benefits of this better fuel head?? I am open to any mod on my fuel system as it is definitely the weakest link of the car(besides the body, interior, brakes and electrical wiring that is )

JoeMag

I'm actually experiencing slightly higher afr's (w/ fuel head mod). about 12.5 at 6200 and 13 at 6700, 415 to ground at 0.8 bar. (964 cams, '91 p/c's, 36mm intake, bb, j-pipe, new injectors, stock timing, 110 gas). I'm at 13 afr idle, so I'm going to drop a little to ~12.5 idle afr and see what happen on track. prior #'s were dyno, so should drop on real road driving.

interestingly, when i turned on the andial, it really didn't change much wrt afr's.

walden

Thanks for the input. These readings are with the andial turned off. If I lean out the mixture more to get less fuel on boost would that not make my idle mixture to lean? Idle is rich at start up but after complete warmup it is high 15's. Is the adjustable WUR the only way to get the correct ratio's? Has anyone seen turbo krafts advertisement for the soon to be released digital adjustable WUR? Thanks again for the advice.

SGOGT4

Stephen -

I spent a couple of hours out on the road with the wideband this morning and here is where I am at. Running the fuel head mod with my Andial turned off (or atleast all the way down), I began with my AFR at idle around 12.2 and was seeing almost 13.0 at 6k on full boost in third.

I ended up adjusting the AFR down to 11.8/9 at idle and am still seeing around 12.7 at 6k on boost in third. With the AFR at idle set around 11.8/9 I will find that the car will dip down to 10.4/5 on heavy initial exceleration and cruise along at about 13.5 at highway speeds.

Am I seeing symptoms of an issue elsewhere in the car? WUR? Is there a chance this particular fuel headisn't flowing as it should? Or is it not completely uncommon to have to set the car at mid to high 11s at idle just to keep it undercontrol at redline/full boost?

JoeMag - I played around with the andial also and found a big difference in the midrange and on initial exceleration and very minimal effect at full boost (maybe 0.2 AFR).

DonE

I know Stephen disagrees, but adjusting the WUR will help you control this issue.