reducing spool times

[jrohner]

I run very lean off boost maps (i.e. I am cruising around with AFRs into the mid to high 16s and sometimes touching 17s) which woks wonders for fuel economy. But could it be one of the reasons why my 50-trim seems to be spooling up a little slow.

And here is my timing map, although from 4,500 upwards in the top 3 load levels I need to lean it out and smooth the curves etc. Do you thinking taking timing out when spooling up (1.0 equals no load in this case)?

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What kind of rpm do you get full boost at with the bullseye 50 trim? I was running over 20 degrees timing at 3 grand, and now I'm in the single digits with the stock 2g map. I would say to pull out 5 degrees and try it, pull out another 5, and try it again. I'm sure you could get at least a couple hundred rpms faster spool.

 

[soldave]

I'm getting full boost at about 4,200rpm. I know that's a bit slow and part of it might be down to boost leaks. Getting it a little lower would be nice though. Bear in mind my Evo 1 has a 8.5:1 compression rate which I think is different from the 2Gs.

 

[aero_sallee]

I'm getting full boost at about 4,200rpm. I know that's a bit slow and part of it might be down to boost leaks. Getting it a little lower would be nice though. Bear in mind my Evo 1 has a 8.5:1 compression rate which I think is different from the 2Gs.

2g's are also 8.5:1. 1g's are 7.8:1

 

[soldave]

2g's are also 8.5:1. 1g's are 7.8:1

Shows how much I know about DSMs!

 

[dwdsm]

A "classic" Evo.. nice!

 

[xxsupralvrxx]

wow that is a nice lookin evo

 

[soldave]

Thanks guys. I'm pretty pleased with it.

 

[Car Cannibal]

I was refering to big twin scroll turbo's like 72mm + with a minimum of .85 housings to 1.1 etc so the actuated port block off would be worthwhile and allow you to run a monster housing for big top end gain.

BTW, preturbo injection also helps spool up when done properly.

 

[tkelly27]

Leaner doesn't always put more heat in the exhaust. My old yamaha atv was really cold-blooded and needed the choke (enrichment actually) on for a few minutes before it would run decent. With the choke on, more than a foot of the the exhaust glowed so red you'd think you could see through it. No it did not glow like that once I turned the choke off.

How would a huge intercooler ever HELP spool? When I finally ditched the side-mount for a huge front-mount, my spool rpm went up about 300 rpms.

Burning fuel in the exhaust manifold is different than running a lean mixture. Burning fuel in the manifold is the basis of "bang bang" systems for rally cars which is also an effective way to keep a turbo spooled up. Leaner does always put out more heat than a system that's not dumping fuel into the exhaust : D

I've always noticed a decrease in spool up when going to a bigger IC. I attribute it to the engine being able to suck through the bigger IC better under off boost conditions, but that may not be so. Your mileage may vary.

Speaking of, has anyone brought up the d-valve?
CSX 321 Buildup - The Dan Culkin Anti-Lag Valve ("D-valve")
more than a little ghetto, but they say it works. I'd be more inclined to use a reed style valve, but, whatever's clever.

 

[soldave]

Speaking of, has anyone brought up the d-valve?
CSX 321 Buildup - The Dan Culkin Anti-Lag Valve ("D-valve")
more than a little ghetto, but they say it works. I'd be more inclined to use a reed style valve, but, whatever's clever.

That looks uber-ghetto! But if it works... Surely if you're running a standard MAF sensor then it would be letting in unmetered air and messing up your AFRs, wouldn't it?

 

[havoc742]

Yeah but if your running a dsmlink you could tune your low rpm map based on your wideband readings.

 

[aero_sallee]

That looks uber-ghetto! But if it works... Surely if you're running a standard MAF sensor then it would be letting in unmetered air and messing up your AFRs, wouldn't it?

Those cars are speed density, so they are lucky there.

 

[asd_gst]

race from a roll brake boost helps alot but it is hard on your brakes

 

[gixxerdrew]

what kind of brake boosting you doing??

 

[Stapl3]

The kind where you push the brake pedal and gas pedal at the same time while cruising? How else is there?

 

[dsm-onster]

He probably is wondering how you can brake boost while rolling at a fair speed. Actually, I got that impression he was suggesting to do this from the post too at first. . . This is why proper puncutation here is a rule.