turbo lag

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craybait
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turbo lag

Postby craybait » Tue Feb 01, 2011 10:51 pm

t2 back on road with rebuilt,balanced engine front mount intercooler, blitz boost controller,doesn't start to pull till about 3500 rpm so is slow off the mark very disappointing to drive especially when you read about turbocab smoking in second[well done] the mechanic thinks the lag may be from the long and daggy intercooler piping?any thoughts[my t1 turbo cab is much quicker off the mark]

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bmgjet
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Postby bmgjet » Wed Feb 02, 2011 6:55 am

What turbo you running. mines got long intercooler piping and is on full boost 14psi at 2800rpm.

Just had to keep the intercooler piping on the smaller side so there wasnt too much room to fill with boost.

spangleking
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Re: turbo lag

Postby spangleking » Fri Feb 04, 2011 10:34 am

When you rebuilt the motor did you rebuild the turbo unit?
Turbo units like to run hot, so a cold start wont spool up quick.
The Intercooler provides the cool air that expands in the CC.
The length may affect it but I would look to the turbo unit itself?
Does it smoke much idling at the lights etc or when caning it?



craybait wrote:t2 back on road with rebuilt,balanced engine front mount intercooler, blitz boost controller,doesn't start to pull till about 3500 rpm so is slow off the mark very disappointing to drive especially when you read about turbocab smoking in second[well done] the mechanic thinks the lag may be from the long and daggy intercooler piping?any thoughts[my t1 turbo cab is much quicker off the mark]

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bmgjet
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Postby bmgjet » Fri Feb 04, 2011 5:28 pm

Fitted a new boost controller to my car today.
With the controller off it doesn't reach 12psi till 3500rpm.
Suspect its because the waste gate slowly opens instead of staying closed till I reach the desired boost.

With it turned on works the same as other boost controller and reaches 15psi 2900rpm. But with out spikes now.

turbocab
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Postby turbocab » Fri Feb 04, 2011 6:27 pm

what size wheels/tyres are you running have you increased the size recently?
perhaps try wiring the waste gate flapper hard shut and very carefully go for a drive and see if it boosts up quicker,at the very worst it will just fuel cut when it overboosts.
my intercooler piping is relatively long and 50mm in diameter and mine still boosts up fairly quick and as you said smokes em up on 13 in wheels and chalky old tyres but that did require a violent downshift and a frantic right foot aplication :twisted: :twisted:

city_cabriolet
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Postby city_cabriolet » Sat Feb 05, 2011 2:40 pm

hehe, watchout with torque steer when dumping it, the t2 has decent power, and will happily yank to the left.

guess thats where the lsd comes in

Sub_Frequency
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t2 should be smoking easy

Postby Sub_Frequency » Sat Feb 05, 2011 6:31 pm

thats suprising to hear that you are experiancing so much lag :(
definately would be taking almost all the fun out of that lil car!

any chance of some pics of what your running? :)

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James
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Postby James » Wed Feb 09, 2011 4:34 pm

When you work out the physics of it, the volume of your intercooler piping makes next to no difference. Consider a couple of meters of 50mm tubing, thats ~4 litres in volume. A city engine at 3000rpm uses ~1800 litres per minute, or 30 litres a second of air, assuming 100% volumetric efficiency. So while it will make a small difference, its unlikely to be significant if your piping is free of restrictions.

It sounds like you might have a leaky wastegate, or leaky turbo (does it sound like a tractor?)

I suggest you do what turbocab said and wire the gate shut, and see what that does.

craybait
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turbo lag

Postby craybait » Sun Feb 13, 2011 9:16 pm

turbo was rebuilt running 13 inch wheels,car was on dyno when not quite run in since then have added a plumb back in blow off valve with some dodgy looking piping so will try all the above suggestions thanks guys

craybait
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turbo lag

Postby craybait » Wed Mar 23, 2011 5:01 pm

about to tackle the above problem,step one is to put stock intercooler on,then work from there.Thanks again for the input.The recent hunting problem rectified by finding throttle body not closing,the mechanic had to re torque the head,so suspect the little prick at radiator shop fanged the new not run engine when cold and had a backfired

turbocab
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Postby turbocab » Wed Mar 23, 2011 6:58 pm

that is why i now tell anyone working on my car on the rare occurrence that i dont do it my self that my car is not to be driven under any circumstance.
i have friends that will remove the computer and make the bastards push it around their workshop.

a_spec
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Re: turbo lag

Postby a_spec » Wed Mar 23, 2011 10:45 pm

craybait wrote:t2 back on road with rebuilt,balanced engine front mount intercooler, blitz boost controller,doesn't start to pull till about 3500 rpm so is slow off the mark very disappointing to drive especially when you read about turbocab smoking in second[well done] the mechanic thinks the lag may be from the long and daggy intercooler piping?any thoughts[my t1 turbo cab is much quicker off the mark]

Hey brother,
What was exactly done to the motor in the rebuild? Were the cams modified? Are they standard pistons or forged? What size intercooler and from what model? What turbo was rebuilt, the standard turbo? If it was the standard turbo, was it rebuilt to exact standard specification? Was the block bored out? Sorry if info has been posted elsewhere. Im new here and still catching up.

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James
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Postby James » Sat Mar 26, 2011 11:45 am

turbocab wrote:i have friends that will remove the computer and make the bastards push it around their workshop.


Thats a good idea!

craybait
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turbo lag

Postby craybait » Thu Apr 14, 2011 7:51 am

motor complete rebuild,original pistons machined for isuzu rings everthing balanced including cluth,the culprit is the turbo it had a$ 1500 flow/rebuild job on it so it boosts from 4000 so it flys from 4500 to 6000.Very narrow rev band ,I think the previous owner aimed for drag racing.We changed back to original intercooler ,no difference.

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James
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Postby James » Thu Apr 14, 2011 8:03 am

What turbo are you running? A t25 or something?


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