Air fuel ratio

Where is everyone keeping there are with there set up....I have read that 12.1 is a safe rario..but why do some people drop there are to 11.1 ...

From what I've always heard 11.5-12:1 is the typical recommendation. Some people might run it rich to be on the safe side just for peace of mind.

Where is everyone keeping there are with there set up....I have read that 12.1 is a safe rario..but why do some people drop there are to 11.1 ...

Good question. No reason to, IMO. Fuel makes for an inefficient mixture cooling medium, and combustion doesn't ignite/burn all the fuel, at the ratio, if those were the reasons/excuses of some.

12.1 is plenty safe.. your looking for no knock.. thats the issue

Using DFI 7 with wideband control. Target a/f Ratios

Pump Gas (93)
IDL 14.0:1
Cruise 14.7:1
5" Vac 13.5:1
0"vac - 5# 12.5:1
6# - 9# 11.8:1
10# - 20# 11.5:1
Total timming at boost 17 deg

C-12
IDL 14.0:1
Cruise 15.0:1
5" Vac 14.0:1
0"vac - 5# 13.0:1
6# - 9# 12.5:1
10# - 20# 12.0:1
Total timming at boost 24deg


These number gave best dyno results with 355 and t-88, .96a/r and 4" down-pipe.

But not all combos react the same way

Preacher Bryan

Using DFI 7 with wideband control. Target a/f Ratios

Pump Gas (93)
IDL 14.0:1
Cruise 14.7:1
5" Vac 13.5:1
0"vac - 5# 12.5:1
6# - 9# 11.8:1
10# - 20# 11.5:1
Total timming at boost 17 deg

C-12
IDL 14.0:1
Cruise 15.0:1
5" Vac 14.0:1
0"vac - 5# 13.0:1
6# - 9# 12.5:1
10# - 20# 12.0:1
Total timming at boost 24deg


These number gave best dyno results with 355 and t-88, .96a/r and 4" down-pipe.

But not all combos react the same way

Preacher Bryan

What is your combo.....would like to no....doing a 355 aswell

some high heat inneffecent setups like a bit richer setups like the eatons.. most lightnings and cobras start heading the other way when your leaner than late 11's or so.

What is your combo.....would like to no....doing a 355 aswell

355 LT1, DFI 7 with wideband control, h-beam, forged crank, J&E pistons -24cc, all studs, cometic head gaskets, ported LT1 manifold, 58mmTB, C&C LT1 heads (flow 284 @.600 on intake, 233 @ .600 on exhaust, open combustion chamber (about 62cc now), 2.02intake 1.60exhaust.

Cam is a custom turbo design based on a 114 lobe seperation and .560/.560 lift (don't know the other #'s on it right now), mondo blow-off valve from Vortec, 44MM wastegate, t-88 turbo with .96a/r modified square flange, top mount like an SVO (over dr valvecover) with about 4" down pipe, big injectors, total eliminator pro fuel system from Aeromotive, #10 out of sump in tank to pump, duel #8 going into fuel rails, duel #6 out to pro regulator, #6 back to tank (over kill on fuel system in case I need it), t-400 with about 400 stall, 4:10 12-bolt and 28" tall tires, lost of tube in the suspension, no p/s, no a/c.

I think that is the basic. never over 16# of boost yet - need bigger injectors. Car is street leagle and all numbers are on pump gas (93) this winter I am going to make a couple dyno runs on c-12 or c-16 and turn the boost up. The car is street legal but I have skinnies on front, ET streets on back with bead locks all the time ( not daily driver ). The t400 took about 150 rwhp from me, but allowed me to stay in boost and only shift twice (I tore up my six speeds) Overkill? Yes. Fun? Yes. Do it again? NO!!! I would buy or build an airplane..... Roll-bar, harness, IHRA rules, (I do not street race), Cool car, light, nice in and out, but for racing and cruising only. Not hard to drive, just limited use.

I built a car for my wife (94 Z-28), simple 42# injectors, 383 from Nu-teck, procharger and 13#'s of boost. Ed Wright got about 500 Hp out of it and almost 20MPG!!! All with ac and everything, fun and easy to drive. :eek:

I hope this helps. There are a lot of smart people on this board that helped me out and I can't thank them enough. When it comes down to it though, I like to fly and build airplanes. :cool:

Bryan

....most lightnings and cobras start heading the other way when your leaner than late 11's or so.

Agreed. Most L owners like to see 11.8-to-1.

12-12.5:1.

Rich

Do you allways want 12ish AFR NO mater what power you are making...

HEy wingnut, any pics? I had a guy send me his pics of a single turbo monted over the valve cover, I reall liked it, and If I could have I'd do twins the same way!

HEy wingnut, any pics? I had a guy send me his pics of a single turbo monted over the valve cover, I reall liked it, and If I could have I'd do twins the same way!

SMOKNZ, go to http://community.webshots.com/user/turbota
it is my webshots page. I will update the pics Wed. However, there are plenty of good shots there right now. I can also e-mail others to you.


Bryan

SMOKNZ, go to http://community.webshots.com/user/turbota
it is my webshots page. I will update the pics Wed. However, there are plenty of good shots there right now. I can also e-mail others to you.


Bryan

great looking setup Bryan :cool:

You must have emailed that pic to me a couple months ago when you were building it. Now thats some creative fabrication. Looks awesome!

You must have emailed that pic to me a couple months ago when you were building it. Now thats some creative fabrication. Looks awesome!

I think I do remember doing that now that you mention it. Back in the summer right? Any way, I would like to do a duel turbo as well with all accessories mounted on bottem of engine. Would require hood mods on TA's and maybe Camaros if large turbos are used.

Check this out. Duel turbos mounted over v-covers, 2 1/2 or 3" max d-pipes back down firewall or between #5&7 and #6&8. Easy, real easy. The only trick is mounting all accessories in none factory positions. For a race car, LS1, or someone who does not care about AC, very simple!!


Bryan

I made mine with the accessory bracket in place, I deleted the AC though. I modified a 1LE pully bracket to make a little more room for the downpipe, and it worked really well. My dream though is to make some stainless headers and use those nice Burns short turbo collectors with the double slip joints and a round stainless header flange so I can weld the tubes all the way around from the inside. That was the most challenging part of the headers was getting round tubes sealed on a D port. Outside ones were easy, just the inside (3,5 and 4,6) were a pain to get totally sealed. The collector was another PITA. I welded it from the inside and out as still ended up with holes all over. I think I spent more time sealing up leaks than making the actual header.