Target AFR check
 

hay guys,

Im about to clean up my tune (its way rich) and just want to make sure Im shooting in the right place

I have 98 octain gas (yes we get that at the pump)
13B REW Bridge port
T51R SPL
4 inch exhaust
4 1680cc inj

I dont have a EGT to go by so am a bit limited.

Does this sound about right?

0 psi- 12 AFR
5 psi- 11.7
10psi - 11.5 AFR
15 psi- 11 AFR
20psi- 10.5

What do you think is reachable at idol with these large primaries?

I don't think your 98 RON is much better than 93 octane US grade fuel, which is RON rating + MON rating / 2 .

I agree with arghx your gas uses different rating system and works out to around our 93 premium. As far as your afrs they sound about right. 20 psi isn't generally considered safe on pump fuel alone. I run 11.1 at 20 psi with water injection. I would go with high 10's even at higher boost. Power really starts dropping off more once into the 10's and it's more likely to misfire especially if your ignition system needs work.

Gasoline 10.8-11.2

Car is only tuned to 1 Bar...sorry should have mentioned that.

What are your thoughts on Idle? this is the biggest problem, being way to righ at idle.

Also just out of curiosity, how on earth do these cars over in japan end up making 800+hp on pump gas? Are they using a crap load of meth injection?

For idle i would run 12.5 to 13.5. You tune idle by sound and smoothness not so much by afr. Don't worry about blowing the car at idle. If you go too lean it just won't run smooth. And if you go leaner it will just shut off. Depending on your ecu and primary injectors you might need changes made to your injector settings.
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Also, I would run higher 11's all the way up to 10 psi not just to 5 psi. Then mid to low 11's up to 15 psi.
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I Never noticed 800 hp rx7's being a common thing even in japan. Maybe skylines or supras.

I have 1680 cc primaries as well and it idles nicely at 800 rpms BUT the AF is in the low 11's. Any leaner does not work well for me, I would have to raise the idle but I like the car idling under 1000.

Anthony

I don't care for an 800rpm idle. I like high idles so that the bearings are floating on higher oil pressure at all times.

-J

Gorilla Race Engineering! :)

What standalone are you using?

ECU is a Power FC.

The car has a very agressive bridge port so wont idle under 1200-1500 very well. My biggest problem is cold starting. Its dumping WAY too much fuel in. Idle and cruise are the next biggest issue. On boost isnt too bad, but Im going to check the whole map anyway. Just waiting for my wideband.

I got my wideband in and took a quick look at the car today.

Short story is that its WAY too rich.

Idle is floating around the mid to low 11s at 1400rpm and I cant get the afr any lower no matter how much fuel I take out and Duty is around 6-7%. If left idling for about 4-5 minutes, it will flood out and stall.

AFRs are in the mid to low 10s on boost.

Does anyone with 1680 primarys mind sharing your injector settings to get them to idle with less fuel? Also do you have these flooding problems at idle?

Im going to sort out the rest of the map in the next few days.

Are you running the pfc? And have you tried negative lag?

If you plan to keep running pump gas, get rid of your 1680 primarys for 850's. You have no need for 1680x4 on pump gas. ***GET A/I***

If E85 is available, switch to that and keep the 1680x4.

No I havnt tried negative lag yet. Im going to book some dyno time soon and start from scratch with the idle first, then the rest of the map.

I have the 4x1680s for a C16 tune for drag racing and Id rather not have to swap out injectors every time I want to switch tunes, and unfortunitly I dont have unlimited money to spend on the dyno.

Understand. I assume that you only run C16 for drag racing because of the fuel cost?

You know that if you switch to A/I or E85, you could stay on pump, run with 1 tune, then forget about it?

Yeah thats the main factor, and that C16 has to be brought in from Australia in 18L drums, takes about a week to arrive and is not road taxed and therefore illegal for the road (my car is driven to and from the track).

AI is on the cards for sure, but would mean missing a few track sessions to pay for it..... and I like racing :) :icon_tup:

We also cant get E85 here. The only thing close we can is E10 and even thats hard to come by.

Ahh the joys of living on a remote little island in the middle of f'ing nowhere :lol:

Haha, I live in Hawaii, on an island with a population of 60k. I am one of two FD's on the island, and the other one doesnt even run. I know how you feel bro. :D