Is it lag or something else?? Help please
Turbo Mini Forums

Howdy Everyone,

1132 - Garret T2 High flowed, not sure what other specs you need. Running Pulsar dizzy re-curved, 300zx intercooler, 10psi comp 9.5:1 compression, stock Blow Off Valved, etc. Mk1 S valves, k-lined guides, head has been worked.

What is happening is that when I take off in first, all good, shift to second and if I shift then nail it its kind if sluggish then whooosh, takes off like a jet... shift to third, nail it, same thing. If I dont nail it (I mean, if I shift then slowly press the Go pedal until its flat to the floor, no issue... smooth powerful all the way) its only when I want to shift and slam on the pedal that it 'hesitates'
Its not like a miss or anything, its just like ... no turbo or power then takes off.

Im also wondering if its the blow off valve (dump valve) could that be slowing the turbo down? I wouldnt have thought so... its a stock metro turbo plenum with the BOV in it.
When I shift, the BOV makes a sound like foo-fooo-foooo instead of a whooosh sound of air. This changed when I put on the air filter. Take the air filter off, and the BOV sounds like WHOOOOSH or psssht if you get my meaning.

Its a Rover EFI tank, malpassi rising rate reg sitting on about 4.5psi on idle (not sure when it gets on boost cant see it)

Any ideas? Tests? Thoughts?

I have orderd a gasket kit for the HIF44 Turbo (to replace seals, etc) just in case.

From dump pipe into exhaust is just a slip joint so there is a bit of a leak, but dont think thats an issue (is it?)

Thanks,
Peter

1132cc Turbo ~120 bananas ATW - Fun Fun Fun

peter i think the standard BOV in the plenum is giving you this issue.... blank this off

It could be leaning off after the gearchange.

Have a look at the logs in this post. It's from an NA engine but I expect all SU carbed engines suffer the same.



Try different oil in the dashpot.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I agree with paul, had a similair problem with an N/A Mini of mine after fitting a K&N filter, the engine would die off then pick up. Changed the needle and all was fine.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


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That "foo-foo-fooo" sound could be the turbo stalling as your not dumping the air. The original BOV is only there as an over boost proctection (I think its set to 8-9PSI- stand to be corrected though). If you want to run more boost than this then you need blank this off.

Fitting a dump valve will stop your turbo stalling and will reduce lag as its continues to spin throughout the gear change. From what you describe, it sounds like lag and the noise is turbo stalling.

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1/4mile in 13.2sec @ 111 terminal on 15psi

Get a nice big Dump Valve fitted! Chav tastic.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


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Split Rims? - http://www.force-racing.co.uk/

Thanks for all the replies guys. Dashpot oil is easy, so ill do that too. Ill get the new BOV and blank off the standard one.

Ill read those posts about the leaning out, thanks Paul... will be working out both needles, mix and everything on a dyno tune.

Cheers,
Pete

1132cc Turbo ~120 bananas ATW - Fun Fun Fun

Check the ignition timing. Maybe too retarted down low. Just a suggestion.

I rekon if you have the funds, inject it! It is so much easier to muck around with to get it right.

Edited by apalazz1275 on 16th Jun, 2008.

Adriano

You’ll lose a lot of money, chasing women.
But you’ll never lose women, chasing money.

Aside from the noise, It sounds like the carb imay be lean when you stomp the pedal. Does a similar thing happen if you cruise at 2000rpm and stomp the pedal? O2 sensor will tell you if its leaning. Also agree with the advance comment, It seems to help things if the advance comes on a bit quicker.

I had a lot of trouble with that until I moved the shoulder of the profile up a lot. thicker Oil can help but even 40 wt did not stop this completely. Remember that most special needles )e.g. Avonbar 10psi) are set up for T3's and dont give enough fuel at lower rpm when a T2 is already blowing.

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The little MT dump valve definitely wont take much to blow.I have had mine blowing on acceleration,running about 9lbs and it blasts when i lift off after WOT.No problem with lag in these circs tho,so I side with the lean mixture view.

Could the vac advance be making it worse? Should I take it off and see how it behaves?
Ill get her onto a rolling road to tune it. Needle, mixture (a/f), etc... I put some more oil in the dashpot, but its not thick...

Turbo Tel - "Does a similar thing happen if you cruise at 2000rpm and stomp the pedal?" Yes I am pretty sure but will double check.

Fark it, ill replace the dump valve with a new one, put a kit through the carb, then rolling road tune and should be all set (I hope)

Peter

PS: Will post updates soon as I sort it.

1132cc Turbo ~120 bananas ATW - Fun Fun Fun

Ok, dashpot oil didnt help (maybe a TINY bit) so I bought a new Dump valve to fit and the carby kit.. (gaskets)
Ill fit those up and put it on the rolling road to tune properly.

More to come soon!

Pete

1132cc Turbo ~120 bananas ATW - Fun Fun Fun

mine is like that if i adjust the DV to blow of to much boost as the turbo has to make it back up again.

but as other posts get needle right and timing then look at other things like the DV, ajustable ones are better as you can let out just the right amount.

always looking for them bigger bunches of bannanas

Ok lads, new BOV fitted and stock one blocked off. Got an adjustable 'Drift' BOV.

Something VERY strange happening now... bare with me...

Now I only get the 'lag' in third gear... if I slowly wind her up in third, then jump on the go pedal it still hesitates and then goes like a jet... ill put this down to tune.

BUT! Here's the weird part.
Since fitting new BOV and blocking old one, the idle has gone up 300rpm and on my guage the Vacuum is on 10hgm instead of 20hgm (where it used to be)
ALSO... and its NOT my imagination... it pulls harder than ever... I went for a rip, and it was lighting up rubber with the same type of driving as before... yes its a 'cooler dryer day' but jesus its going REALLY hard.

I am getting a massive raw fuel smell though, and putting this down to seals in the carby... which I will rebuild.

So any ideas on the idle and vacuum changes?
If I have a leak somewhere, would the idle increase? No right, would decrease and idle rough... right?
Could I have had a leak before and now its fixed?

I dunno, all I know is idle is higher, vacuum lower and she absolutely hammers now...

Thoughts?

Peter.

1132cc Turbo ~120 bananas ATW - Fun Fun Fun

Whatever you have done has given it a richer mixture,hence the better power.What the hell is going on in third gear only must be down to aliens

raw fuel smell is caused buy excessive blow buy via the rings into the sump and out via the breathers.

always looking for them bigger bunches of bannanas

or a carb leak...

Try temporarily blocking off the vacuum hose to the new BOV and see if the islde drops. Oh! and by the way, the factory BOV on the plenumn isn't a BOV but a pop off Valve at around 8-10psi. I suspect that your new BOV could be leaking at idle. This isn't such a problem caus as soon as you accelerate it will shut off the BOV totally. And yes I agree that the third gear lag is down to running fat on pump of acceleration.
Godd luck!! We should cruise some day!

Adriano

You’ll lose a lot of money, chasing women.
But you’ll never lose women, chasing money.

Just a suggestion. Check your static ignition timing, with the vacuum hose off. Let me know what it is.

Adriano

You’ll lose a lot of money, chasing women.
But you’ll never lose women, chasing money.

Ok, definately vacuum leak, the new BOV is leaking like a siv on idle... will take back tomorrow...
Carb is playing up, I know that and have a kit, rebuilding it on Sat.

Third gear aliens for sure... its prolly just laggy but odd really. When I sort the BOV and carb ill see what happens.

Yeah Adriano, let me know mate, im up for it... so is Ben with the 1152 Turbo

Peter

1132cc Turbo ~120 bananas ATW - Fun Fun Fun

Yeah no worries champ.

Just had a run in with Tom Fenton.

I just can't believe some people. I mean you make a little mistake like posting up two topics about similar things. And in a sarcastic way make you feel like their on top of you.

Mate whatever you need, just ask and i'll try to help to the best of my knowledge.

Later!

Adriano

You’ll lose a lot of money, chasing women.
But you’ll never lose women, chasing money.

Ok, put in a turbosmart vee port type 2 and vacuum leak is GOONE... 20hgm when I back off the throttle, drives on about 15 and is quick to 0

Anyhow, still having the same issues with the slingshot effect, 2nd and third gear mainly... its not lag, its something else. Ill get it on the dyno asap...

Peter

1132cc Turbo ~120 bananas ATW - Fun Fun Fun

Hi,
What the vaccum at idle, really speaking you should have 20 mmHg and more than that when on over run...
As someone said above I think it the fact the T2 comes in a lot quicker that's catching the carb out..
Cheers,
Gavin :)

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20hgm on idle? I get that only when I blip the throttle and then slowly creeps up a tad.

None of the guys here have close to the vacuum I have in their smallbores... they are all amazed that I have that much actually.

1132cc Turbo ~120 bananas ATW - Fun Fun Fun

Hi,
I never expected a small bore to have less vacuum than a big bore, surely they should all be the same?
The Classic Car guide to vacuum tuning I have photocopied in my tool box says 18-20 at idle if IIRC.
My STD 1275 certainly runs 20, other makes of engine I've tested run 20 too.
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary