running a laggy turbo???

[91-gsx]

i had a quick question about the lag in a big turbo, i understand it makes a big difference in daily driving. but lets say you shift at redline on a gsx or at 8000 rpms, can the stock drivetrain take this kind of shifting? anyway, what rpm are you at in the next gear, about 5000 rpms right? doesn't that mean that if i got a really big turbo, one that takes 5000 rpms to make full boost? i could have it kick in in every gear while at wot? i understand that it might take longer to accelerate out of boost, but once you got on it all hell will break loose.
any information or something I'm missing please tell me.
later

 

[Catbox_95]

Technically speaking, you are correct. However, there still is an issue of lag even though you're in the right rpm range when you shift.

I am having this issue. I have a 57 trim, and I've been working to reduce lag. I just installed a SBR stainless header which is equal length, plus it's port-matched to my turbo, which is also ported. These things dramatically reduced turbo lag, but it is still there.

When I shift at 7,000 rpm, it drops to about 4,500 rpm. This is within boost efficiency, but since all pressure was released out of the system for the short period of time that I let off the gas to shift, there is that requirement of time before the turbo comes on full boost again.

From a stop, my turbo has built full boost by about 4,000 rpm. But even when I shift and it's above 4,000 rpm, there is still some lag because there is no boost in the system.

 

[1fast97gsx]

Lag is overrated. Sure it takes more time to make power, but you also make more power so it pays off. My gas mileage got better with a laggy turbo.

 

[ian7321]

yep gas mileage goes up because it takes a while to get into boost and thus you are kinda running N/T for about 4000 rpm's.

 

[Syndicate13]

This is within boost efficiency, but since all pressure was released out of the system for the short period of time that I let off the gas to shift, there is that requirement of time before the turbo comes on full boost again.
.

Just don't lift.

Lag is overrated, smaller turbos can only make so much power and who really needs 300hp to drive around town?

 

[sweet97]

I've got a laggy turbo, 4300 for 20psi but I run 25+ psi. Stutterbox launch gets me starting at 10PSI and as was stated already no lift shifting keeps you in boost so there is little lost between shifts. For passing just downshift. Mark

 

[JDMFirstGen]

I'm running a Bullseye 57trim and I was hitting 21psi by 3800rpm's. After I installed my cams (Crower stage3's) it was by 4000. I have an SBR equal length manifold but I have yet to put it on because my engine is now out and under construction.

I also launch on a studdor box, which makes a big difference in spool time.
I shift at 8000 with no lift to shift and I see virtually NO lag in between gears.

 

[definitiveno]

High stall automatic for the win against lag

 

[JDMFirstGen]

Slushboxes are for women and paraplegics.

 

[91-gsx]

i like the no lift to shift feature because i bet it works great for turbo cars, the only thing is that i have a stock tranny and i am not thinking of upgrading it any time soon. do you think the stock tranny can take that kind of abuse? if it can then i have been missing out, i noticed srt-4's and other fwd cars have it as well, but if they have to much power the tires break loose, with our awd something in the drivetrain would break loose, maybe i am just thinking that the tranny is really weak when it is not. another thing, can you go to 8000 rpms with the stock drivetrain? i had my eprom chip made for a rev limiter of 8250rpms just in case, so it is possible, but not on the 14b .
thanks for any help

 

[JDMFirstGen]

i like the no lift to shift feature because i bet it works great for turbo cars, the only thing is that i have a stock tranny and i am not thinking of upgrading it any time soon. do you think the stock tranny can take that kind of abuse?
...another thing, can you go to 8000 rpms with the stock drivetrain? i had my eprom chip made for a rev limiter of 8250rpms just in case...

I would not do this on a stock tranny, I've got a shep one with a warrentee so I beat the shit out of it.

Drivetrain? If you mean valvetrain, then yes sort-of. How High you should rev depends on your engines ability to hold together and where you can make power at. I'm running Crower race cams that can make power at 9000+, but stocks won't help out past 6500-7000.

Also, what you have to worry about in high-rev applications is valve float. You would need to get better springs and maybe retainers to avoid this. As a note though, I'm running stocks with my cams hitting 8200 with no valve float or loss of power.

If you do upgrade, don't get crower springs as they aren't much better than stock. Only about 3psi in spring seat pressure difference.

 

[definitiveno]

Slushboxes are for women and paraplegics.

Slushbox? This ignorance can only come from some one who's never been in a built automatic car.


I have rock hard shifts and better throttle/turbo response than you. Keep talkin.....

 

[definitiveno]

High stall automatic for the win against lag

BTW if you reread my post I was just messing around (see this smilie for reference to said messing around). I know auto's are not for every one.

 

[sweet97]

Slushboxes are for women and paraplegics.

A properly built automatic will most often beat the stick. Many of the quickest cars are run with automatics. MarkPS: I am a former Starion/conquest owner. Someday I hope to build my dream car and it would be one of those with the "slushbox" and 4.22 gears with an OD tranny. Possibly with a 4g63 since many already run the 4g63 in those cars.

 

[JDMFirstGen]

Slushbox? This ignorance can only come from some one who's never been in a built automatic car.


I have rock hard shifts and better throttle/turbo response than you. Keep talkin.....

For those who took my comment seriously... It was a joke!

For a street car, I just like stick just because it is more fun. I didn't mean for your feelings to get hurt .

In any car running serious times, a well set up auto is a much better option.

If you think I have no experience, I co-built a drag car with a friend. It was a 69 nova with a stroked 454, turbo 400 tranny(automatic), 3500rpm stall, 4.56's and spray. The car did 11.67 off the bottle with a misfire and no traction. The day we sprayed it ran 12.7 no spray due to carb problems, and 11.44 spraying with the same problems.

I have no experience with fast turbo auto's minus riding in an 11sec talon.

With all this said, I'm keepin' my stick.

 

[definitiveno]

For those who took my comment seriously... It was a joke!

blah

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You must be logged in to view this image or video.

Next time add some humor in your jokes, . Sounds like the only thing funny to you was every one who has an automatic, . I'll try not to be so oversensitive next time, .


(if you take out all the 's, my post almost looks serious )

 

[JDMFirstGen]

...







...happy?

 

[4G63 For Me]

I have a SBR GT-14, hit 20+ PSI by about ~5000 RPM. It does have a little lag between shifts, but the here is the way I see it. If I'm racing, I can drive so I have little to no lag. Stutterbox helps starting off, and if I shift around 7500-8000 (last time I raced I took it to 8300 and the car felt like it could go past 9000+, but ended up spinning some rod bearings, probably not related) there really isn't too much lag on the respool (gotta love dual ball bearing). I'm sure that would be even less if a) I ran no lift to shift b) got a better exhaust manifold (running stock, unported).

Driving on the street, the 5000K spool up really keeps me out of trouble. Not constantly boosting around town, the car has enough get up to go in 90% of normal driving situations, and if I'm merging onto the interstate or passing, I just downshift.

It's all about how you drive the car. If you need power, stick in your RPM range and lag isn't a factor.