18g Power/Spool Questions.

[BaddAssGst]

It seems like my 18g isn't pulling as hard at the beginning of the power band like it should. I've only ran a 14b and 18g on my car now so that is all I can compare to. If I'm in 4th and downshift to 3rd at 50mph (Mind you 2nd ends at 60 so 3rd would still be 4k rpm or so) it seems like that from 50-60 it doesn't pull like it should. If I'm going 60 in 4th and downshift, it's a completely different story and the car pulls quite hard.

Am I just to picky? I can't think of anything else that would make it seems :slow:?

 

[tonygst]

I hate to ask a real obvious question but you have done a boost leak test? Also how long have you had this 18g? Was it pulling harder before? Or did you just recently install the 18g?

I don't think your being picky, your 550's aren't cutting it for that edge your wanting.

 

[BaddAssGst]

I hate to ask a real obvious question but you have done a boost leak test? Also how long have you had this 18g? Was it pulling harder before? Or did you just recently install the 18g?

I don't think your being picky, your 550's aren't cutting it for that edge your wanting.

I can't say for sure because everything went in at the same time, the last oh say 2,000 miles. According to my logger, my IDC isn't over 100%, in fact I'm only getting about 74-80% at 18psi, which leads me to believe something isn't right? I would think that they would be alot closer to 95% or so.

A boost leak test was done recently and there was only a small leak which was around the TB, which I presumed was shaft seals. It doesn't bog in any gear and builds the boost just fine (i see about 18psi by 3500-3600). It just seems that it should pull harder then what it does.

 

[JiggahMan]

Tuning? Also, there's a reason why the 18g is said to be a 16g with the lag of a 20g.

 

[BaddAssGst]

Tuning? Also, there's a reason why the 18g is said to be a 16g with the lag of a 20g.

I'm fairly decent at tuning so I would have to say it's not but I guess there is a chance. It just seems like there are a couple points in the rpm band (rpm wise, the turbo would be spooled on the downshift) that it should pull harder then it does. I don't think the lag is all that bad on it. It's got a fully ported Evo manifold and the turbo is pretty well ported itself.

 

[JiggahMan]

I'm fairly decent at tuning so I would have to say it's not but I guess there is a chance. It just seems like there are a couple points in the rpm band (rpm wise, the turbo would be spooled on the downshift) that it should pull harder then it does. I don't think the lag is all that bad on it. It's got a fully ported Evo manifold and the turbo is pretty well ported itself.

Since lag isn't the factor, I'd say it's most likely tuning. Put up a log and we'll find out.

 

[dsm-onster]

Tuning? Also, there's a reason why the 18g is said to be a 16g with the lag of a 20g.

I'm not flaming but I have proof to the contrary. There was virually no difference between the spool time on my 18G and my SMALL 16G. I was running at the same psi with the small 16g as i am now with my 18g and i was getting 9-10 counts of knock at around 5800 rpms. Now i am getting none (with no change of tune or other hardware). this tells me that the turbo is spinning at a significantly lower rpms so not whipping the air into a heated frenzie.

I have FP2X cams in the mail along with manley springs and retainers. I will be revving her to 8500+. I'll see if she can support that kind of flow. I'll post my logs then.

I do agree that the problem may lie in the tuning.

18psi at 3500 rpms doesn't look right to me. I am running at 22 and i get there by 3100. I ran her at 16 psi when i was breaking in my SBR 3500 clutch. she didn't pull very hard at all in the beginning of the mid range. She crept to 19 psi or so too. When I turned up the boost the creeping left and she feels much happier through out the power band. she pulls significantly harder than my SMALL 16G at the same boost levels.

One other thing... are you sure you're not creeping to 18psi? I mean, when boost comes on, does it jump to say 14psi then more slowly rises to 18 psi?

P.S. Porting and clipping your 18G will make your stock cams and intake restrict you a bit. Porting and clipping would explain why you dont have full boost until 3500rpms and you don't have much in the beginning of your power band (because you shifted your powerband). I should have looked at your mods before I posted

 

[mavisky]

My 18g is very responsive. Only laggy below 3000rpm. Takes off like a rocket anywhere above that for a stock looking turbo.

 

[BaddAssGst]

If it ever stops raining here, I'll get a log posted up.

The thing is that it is a steady boost and holds 18psi until redline. It doesn't creep at all. What I :think: is that it is those first few PSI that make it seem slow. I can't say for sure but I would think on the downshift, it should pull quite hard.

 

[dsm-onster]

If it ever stops raining here, I'll get a log posted up.

The thing is that it is a steady boost and holds 18psi until redline. It doesn't creep at all. What I :think: is that it is those first few PSI that make it seem slow. I can't say for sure but I would think on the downshift, it should pull quite hard.

I really think because of the clipping and such that it just doesn't wake up until later. I'd be very interested in logs. I'm thinking that i should have ported and clipped my 18G.

 

[BaddAssGst]

I really think because of the clipping and such that it just doesn't wake up until later. I'd be very interested in logs. I'm thinking that i should have ported and clipped my 18G.

Fp told me the wheel already came pre-clipped when I ordered it. I did alot of reading about it before I ordered it and I figured I'd lose a little spool-up and gain top end (which was mainly what I was interested in) with it clipped.

Ground looks fairly dry out today so hopefully I'll be able to have a log up tonight.

 

[dsm-onster]

Fp told me the wheel already came pre-clipped when I ordered it. I did alot of reading about it before I ordered it and I figured I'd lose a little spool-up and gain top end (which was mainly what I was interested in) with it clipped.

Ground looks fairly dry out today so hopefully I'll be able to have a log up tonight.

I got mine from FP too. When i bought it, there was a dropdown option for adding a clipping job. My turbine wheel looks exactly the same as my 16G so i'm sure mine isn't clipped even it is a FP 18G.

Give her hell so we can see your tune

 

[BaddAssGst]

I got a chance to get some logs. For some reason, I can't get them in a graph or anything so I'll just type it out. Unless someone has a different way?

3rd and 4th gear pull: 3k-5k rpm, my o2s are steady from .82-.85 and I'm getting no knock, yet still under 10 degrees timing. 5k-6200, my o2s were .80-.74. I was getting like 10 counts of knock so I added some fuel but my timing was still 16 degrees?

---------------------------

I added some fuel from 5000-7000.

The log was about the same as the last one except my 02s dropped from .84 (3500rpm) down to about .76 (6500rpm). I was still knocking up top a little bit so I added more fuel.

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On my very last log I was getting no knock until 5500, .76-.80 for my o2s, and I was getting about 11 degrees of timing. After 5500, I was getting like 10 counts of knock

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I'm getting low timing throughout the power band before it knocks and once it knocks, I get the timing (17-18degrees) that I should. I know it's hard to read but I'm not sure what to do or which way to go.

I'm tuning with an AFC and the rpm points are set as 1k (-7%), 2k (-10%), 3k (-11%), 4k (-11%), 4.5k (-12%), 5k (-9%), 6k (-8%), 7k (-8%).

 

[BaddAssGst]

Got them in a graph, hopefully it shows up now. Thanks guys.

Edit: Well they didn't quite show up in a graph.. I'll see if I can make it easier.

 

[green92gsx]

Try to richen it up in the 3-4.5k range for the spool up and peak torque. Then lean out from there. At least that always worked the best for me.
I can hit 30 psi at 3600rpm on my 18g for comparison.
I will say it really doesn't pick up steam till 4500k or so and can give the "flat" feeling till then.

 

[BaddAssGst]

Try to richen it up in the 3-4.5k range for the spool up and peak torque. Then lean out from there. At least that always worked the best for me.
I can hit 30 psi at 3600rpm on my 18g for comparison.
I will say it really doesn't pick up steam till 4500k or so and can give the "flat" feeling till then.

I'll definitely try that. Like today, it seemed like it pulled better but it still feels like that "flat" feeling your talking about. Once the turbo is fully spooled, the car feels quick but I know I need to get rid of that 1g mas.

Anyway, how do the logs look? Timing advance seems low when I'm not getting knock but advances when I get it? I also tried to richen it up tonight to see if I could rid the knock and from 5000-7000, I richened it up to about -6% but around 6k/6500 I was feeling almost what I thought was fuel-cut like. I set it back to the original settings (-8, -9%) and it didn't do it.

 

[green92gsx]

My timing curve from 5k starts at 21* and peaks 24* at 6k. From there it falls to 17* by 7500k. Thats seeing around 14-15 ms with the 660's. Using a hacked 2g mass and stock fuel pressure. 0-5 counts of knock 3rd gear.

This is what I pulled off some logs from the track over the summer. Keep in mind this is with high boost and race gas.

 

[dsm-onster]

I'll definitely try that. Like today, it seemed like it pulled better but it still feels like that "flat" feeling your talking about. Once the turbo is fully spooled, the car feels quick but I know I need to get rid of that 1g mas.

Anyway, how do the logs look? Timing advance seems low when I'm not getting knock but advances when I get it? I also tried to richen it up tonight to see if I could rid the knock and from 5000-7000, I richened it up to about -6% but around 6k/6500 I was feeling almost what I thought was fuel-cut like. I set it back to the original settings (-8, -9%) and it didn't do it.

I smell MAF overrun...

 

[BaddAssGst]

I know it was either very close or it was getting over run. I have everything to run the GM Maf except the UICP, which I would either have to get custom made or use Dejons, which he wasn't very helpful when I asked him. I'm currently running Buschurs set-up, where the end tanks face the firewall and short route piping. I just don't want to hack my pipes if Dejons or any other option I might have is available. Any suggestions?

 

[mavisky]

My timing curve from 5k starts at 21* and peaks 24* at 6k. From there it falls to 17* by 7500k. Thats seeing around 14-15 ms with the 660's. Using a hacked 2g mass and stock fuel pressure. 0-5 counts of knock 3rd gear.

This is what I pulled off some logs from the track over the summer. Keep in mind this is with high boost and race gas.

What boost levels exactly?

 

[BaddAssGst]

I check my boost levels today and I'm getting 18psi by like 32/3400 rpm. I'm not sure what changed on it but in 3rd it was full by 3400 and in 4th I hit full boost by 3200. The car actually felt good today but it still feels like it's got that flat spot in it.

 

[green92gsx]

What boost levels exactly?

28-31 psi.

Besides logging with the afc to see if your dropping counts, look at your injector pulse width logs. It should start getting chopped up at the same time.