1st trip to the track
Melting Slicks
Joined: Aug 2003
Posts: 3,407
Likes: 400
From: Lakeville MI
So you have 23 degrees in the chip, 10 lbs. of boost, and between 1 and 1.5 degrees of boost retard per pound?
I'm assuming that the 23 degrees in the chip is across the board in the max load column of the spark table.
This gives:
23 - (10*1) = 13
or
23 - (10*1.5) = 8
If I'm getting this right, you're only running between 8 and 13 degrees total advance at 10 lbs. of boost. This may explain the low trap speeds.
I had previously assumed that the 23 degrees that you mentioned was the end result after the boost retard was subtracted. Are you sure you don't have 38 degrees in the chip and 15 degrees of boost retard to arrive at 23 degrees? Be careful until you know for sure what you have.
I'm assuming that the 23 degrees in the chip is across the board in the max load column of the spark table.
This gives:
23 - (10*1) = 13
or
23 - (10*1.5) = 8
If I'm getting this right, you're only running between 8 and 13 degrees total advance at 10 lbs. of boost. This may explain the low trap speeds.
I had previously assumed that the 23 degrees that you mentioned was the end result after the boost retard was subtracted. Are you sure you don't have 38 degrees in the chip and 15 degrees of boost retard to arrive at 23 degrees? Be careful until you know for sure what you have.
Last edited by tequilaboy; May 1, 2008 at 10:36 AM.
Instructor
Joined: Dec 2005
Posts: 188
Likes: 0
From: Riverside CA
I don't think you car like it does at even 23
probably would run worse than stock at 13 or 8
You shold varify timing with a "light"
A tuner can set up a chip on a PC but it does not mean your timing is actual.
probably would run worse than stock at 13 or 8
You shold varify timing with a "light"
A tuner can set up a chip on a PC but it does not mean your timing is actual.
Instructor
Joined: Dec 2005
Posts: 188
Likes: 0
From: Riverside CA
Instructor
Joined: Dec 2005
Posts: 188
Likes: 0
From: Riverside CA
I am realy suprised,
i never heard of a car that ran well on 12* unless it was ideling.
I don't mean that the wrong way, You car is running fast, and it does not seam possible on 12*
Even if you tuner put 23 in the chip, what do you have at the crank?
i never heard of a car that ran well on 12* unless it was ideling.
I don't mean that the wrong way, You car is running fast, and it does not seam possible on 12*
Even if you tuner put 23 in the chip, what do you have at the crank?
Melting Slicks
Joined: May 2001
Posts: 3,014
Likes: 18
From: Raleigh, NC
You can use a Might-Vac brake bleeding tool to put pressure on the vac/boost port of your ignition box to simulate boost. Then use a timing light to verify actual timing while under boost. I would bet that with another 10 degrees of timing under boost, you'll pick up 50+ RWHP.
I don't have a ton of experience tuning boosted L98 cars, but I would think that the motor would take 19-20 degrees of timing at a minimum with 10 PSI.
I'm curious what you are doing for fueling, just a rising rate regulator or do you have a 3 bar MAP and a modified .bin file?
I don't have a ton of experience tuning boosted L98 cars, but I would think that the motor would take 19-20 degrees of timing at a minimum with 10 PSI.
I'm curious what you are doing for fueling, just a rising rate regulator or do you have a 3 bar MAP and a modified .bin file?
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Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
I haven't gotten a chance to get out there yet this weekend.
As for fueling, I'm using a Vortech FMU 6:1 and inline Walbro 255lph. No 3 bar map...and as for the .bin file, if it's something the tuner modified, otherwise I have know idea.
As for fueling, I'm using a Vortech FMU 6:1 and inline Walbro 255lph. No 3 bar map...and as for the .bin file, if it's something the tuner modified, otherwise I have know idea.
Safety Car
Joined: Apr 2001
Posts: 3,525
Likes: 2
From: Houston TX
i.e. 41 psi at idle, 47 psi with vacuum line disconnected at idle (simulating no vacuum / no boost). At max boost (10 psi), the new fuel psi is 107 psi (47 psi base + (10 psi boost * 6:1 FMU). For most injectors, that would damage the internals. I have run many FMUs, but the most increase was with an adjustable unit that gave up to 4:1 (which I ran at ~2.5:1).
Just some food for thought...
Aaron
p.s. I run 21° advance at 25 psi. The car is really happy with mild boost still having very high 20° of advance. But this may have to do with my heads and cam selection vs what you are running.
Instructor
Joined: Dec 2005
Posts: 188
Likes: 0
From: Riverside CA
Silver,
with all due respect..
Why didn't your tuner eliminate the FMU, and the BTM and just make a correct tune on your chip?
I agree with Aaron, your FMU at 6:1 would be almost too much for a 5-6 lb. boost set-up. At 10+ Boost you are at 100+ FP?
I had a set of 22# injectors flow tested and they started to LOCK UP at 75 psi.
I think I saw (another post) that you mentioned that you run 42# injectors. You should not need an FMU if tuned correctly.
If I were you, I would have it retuned with no FMU. (just a boost referanced f.p.r.) and have your max timing set at 28* with your BTM at -0-.
That way you could run conservitive on pump gas 91 with you BTM dial at 1/2. Your total timing would only go to 23* at 10#
You could run some race gas at the track and turn BTM to -0- for more power.
Just my opinion
with all due respect..
Why didn't your tuner eliminate the FMU, and the BTM and just make a correct tune on your chip?
I agree with Aaron, your FMU at 6:1 would be almost too much for a 5-6 lb. boost set-up. At 10+ Boost you are at 100+ FP?
I had a set of 22# injectors flow tested and they started to LOCK UP at 75 psi.
I think I saw (another post) that you mentioned that you run 42# injectors. You should not need an FMU if tuned correctly.
If I were you, I would have it retuned with no FMU. (just a boost referanced f.p.r.) and have your max timing set at 28* with your BTM at -0-.
That way you could run conservitive on pump gas 91 with you BTM dial at 1/2. Your total timing would only go to 23* at 10#
You could run some race gas at the track and turn BTM to -0- for more power.
Just my opinion
Thread Starter
Drifting
Joined: Dec 2005
Posts: 1,309
Likes: 20
From: Woodstock Georgia
I had originally installed the 4:1 FMU plate (I am running the 42# injectors). We couldn't get it tuned with that plate, couldn't get it rich enough by programming alone. The main problem was, that either the emulator or the stock electronics, would not let him program greater than a 50% duty cycle on the injectors. I installed the 6:1 on the dyno, and no issues after that. I'm at 40#'s at idle.
I originally installed the FMU on Greg's recommendation. He had a similarly setup '88 that wouldn't tune either, until they installed the FMU.
I originally installed the FMU on Greg's recommendation. He had a similarly setup '88 that wouldn't tune either, until they installed the FMU.
Last edited by silver86; May 4, 2008 at 05:09 PM.
