Intercoolers and lag?

[Chris Wilson]

Im going from a 2 row to a 102mm blitz lm 3 row, just wondered if i will notice any difference in spool time:)

 

 

You won't notice it, as someone posted earlier, the volume of air the turbo delivers, even off boost makes the extra I/C and / or pipe volume trivial. You can run silly big I/C's and not see much difference in lag time.

[dandan]

I'd be extremely suprised if you noticed ANY difference at all.

[michel lane]

I have just upgraded from a 3 row to a 4row , the difference is about 100rpm , but my temps are down by 15 degrees according to the AEM logs, this allows me to run higher boost.

[Ian C]

A DBB turbo would help because boost doesn't drop boost between gearchanges as much as with a journal bearing turbo.

 

I tried this when testing the T67DBB, and from 3rd to 4th gear, shifting at about 6500rpm, I found that both turbos spun up identically. They took 0.6 seconds to hit 1 bar of boost, and both hit 0psi in about 0.1 seconds from lifting off the throttle to start the gear change.

 

I was surprised that the DBB didn't offer any advantage there but I guess that there is so much exhaust energy going on at that point that it ironed out the differences. DBB is all about lower exhaust energy areas.

 

-Ian

[Kranz]

I tried this when testing the T67DBB, and from 3rd to 4th gear, shifting at about 6500rpm, I found that both turbos spun up identically. They took 0.6 seconds to hit 1 bar of boost, and both hit 0psi in about 0.1 seconds from lifting off the throttle to start the gear change.

 

I was surprised that the DBB didn't offer any advantage there but I guess that there is so much exhaust energy going on at that point that it ironed out the differences. DBB is all about lower exhaust energy areas.

 

-Ian

 

To see any off throttle spool down difference you'd need speed instrumented turbos, which were £1K a pop to do last time I had them done at work

Good to see the turbo speeds though, especailly when going towards the upper limit of the turbos.

 

I may actually have an instrumented turbo at home somewhere of something. Bit tricky fitting the pickup through the compressor housing

[Chris Wilson]

http://www.owendevelopments.co.uk/products/product-detail.asp?prodId=21

 

and

 

 

http://www.owendevelopments.co.uk/uploaded/TurboSpeedSensorSpecification.pdf

 

352 quid plus VAT

[JohnA]

Chris,

 

Have you ever seen one of these in action?

Very cool instrument indeed.

I'd regard this display as very important in any modified turbo.

In my case I'd like to see it next to boost and AFR. More important than inlet charge temps in my book.

[Wez]

I'd regard this display as very important in any modified turbo.

In my case I'd like to see it next to boost and AFR. More important than inlet charge temps in my book.

 

Can you explain why please

[Chris Wilson]

Chris,

 

Have you ever seen one of these in action?

Very cool instrument indeed.

I'd regard this display as very important in any modified turbo.

In my case I'd like to see it next to boost and AFR. More important than inlet charge temps in my book.

 

No, never even seen one in a box, but they plugged them heavily in the motorsport mags.

[JohnA]

Can you explain why please

 

The main reason behind turbocharger failure on modified engines is overspeeding of the turbo's shaft.

Boost values are not a very accurate way to predict shaft speed. They are quite rough - at the same max boost readings you could find yourself below or well above the max safe shaft speed.

A 10% increase in boost could result in 10s of thousands of extra shaft rpm, damaging it irreparably. (actually it is a function of the pressure ratio, and it rises very steeply)

 

The only way to know exactly where you stand on full-load conditions is to have an rpm gauge for the turbo. I've never seen one in action, and this one looks like a decent idea (from their description of how it works).

 

It would also help me validate some theories I've got regarding compressible fluids. There is anecdotal and indirect evidence, but not hard numbers. Same as the relativity theory, that only now are they developing the technology to actually measure the effects in our environment.

 

Setting a boost controller on the bleeding edge would also be more optimal and SAFE. I'd stick this one a bit higher up the scale than an EGT gauge.