exhaust repair or replacement?

[nitroman]

http://www.2kracing.com/product_info.php/products_id/4161

Case closed.

Actually, I think what they are trying to say is this: Imagine ONLY your waste gate. The original J-pipe had a small-opening which the gas coming through your waste gate was forced to flow. With the stiffy it has the whole entire pipe to flow in. Theoretically this could solve the problem.

If your problem is not acute, meaning you only hit 'cut' for a split-second when winding out a gear near redline, then consider the FCD. I wouldn't recommend the FCD if your boost-cut occurs way before redline though, as you'd be flirting with disaster.

[Doug]

I don't think we have enough hard data for the Elan to prove what will and won't work yet.

Think of the exhaust flow as say a river (most people can picture water flowing down a river). The river splits into 2 parallel smaller parts at the turbo with the main flow going thru the turbo and a smaller flow going thru the wastegate.

If the flow thru the wastegate gets to max and it can not accomodate any more then all the rest must go thru the turbo and it is this situation that makes the boost creep.

If you open up the river channel at the wastegate then it can accomodate more and keep extra flow from the turbo side---that's the role of a wastegate.

The inherent design of the car is for boost up to 0.65bar. Since we have turned the boost up we have in essence increased the flow down the river to greater than what it was designed for--and this is what causes the problem and thus the creep. If you design the parts to handle more flow then there is no problem with their function.

Since the Stiffy bolts to the exhaust side of the turbo it replaces the s-shaped pipe between the turbo and downpipe, which is pretty much the flow limiter in our boost range.



Thus put the stiffy on and enjoy more boost without the consequences . . .

Alternatively you can port out the wastegate a bit, but this can only be done so much. The other way is to upgrade the whole turbo and wastegate paths and this would likely require a new part like the stiffy as well, but this would be for Costas-like boost levels!!

[Doc Fizzix]

I don't think we have enough hard data for the Elan to prove what will and won't work yet.

Think of the exhaust flow as say a river (most people can picture water flowing down a river). The river splits into 2 parallel smaller parts at the turbo with the main flow going thru the turbo and a smaller flow going thru the wastegate.

If the flow thru the wastegate gets to max and it can not accomodate any more then all the rest must go thru the turbo and it is this situation that makes the boost creep.

If you open up the river channel at the wastegate then it can accomodate more and keep extra flow from the turbo side---that's the role of a wastegate.

The inherent design of the car is for boost up to 0.65bar. Since we have turned the boost up we have in essence increased the flow down the river to greater than what it was designed for--and this is what causes the problem and thus the creep. If you design the parts to handle more flow then there is no problem with their function.

Since the Stiffy bolts to the exhaust side of the turbo it replaces the s-shaped pipe between the turbo and downpipe, which is pretty much the flow limiter in our boost range.

Very nice

Just a little comment, Doug, you did a very nice write-up but I remember last time I tried to paint a clear picture as well as you did, someone took it as if I was patronizing them. I personal think we need a lot more information like this posted in a clear visual. Nice job, I want my "stiffy" --- what the hell does that mean?

[nitroman]

You want a visual of that? Don't know that anyone's gonna go there!

[Doc Fizzix]

You want a visual of that? Don't know that anyone's gonna go there!

LOL

I was just making a jab at the fact then when I made a similar post someone want nuts on me. I was just trying to be funny, I forget, that is how I get myself in trouble around here

BUT, I would like to get one of the "stiffys" --- Someone let me know

[ailwyn]

BUT, I would like to get one of the "stiffys" --- Someone let me know

Doc

PM Stevo for Stiffy details.

Ailwyn

PS Have the bolts gone yet? Thanks

[pjohn151]

Thanks Doug,

I was under the impression that the actual wastegate aperture was the limiting factor - ie a 16mm dia hole with a gate of dia 26mm, allowing a porting to something like 20mm dia, as in Stevo's write up in fitting the 'stiffy'

now you need to take the turbo off to port the wastegate http://lotuselancentral.com/forum/viewt ... +wastegate

i have rewitten some of the fitting instructions on this page coz its defo worth doing the wastegate porting.

you can take the turbo to your freindly local machine shop and ask them to do it.

or have a go yourself. http://www.buyatool.co.uk/acatalog/Buya ... s_168.html http://www.screwfix.com/app/sfd/cat/pro ... 9&id=36926

the jist of it is you have a 26mm flap over a 16mm hole. you want a 20mm hole or there abouts.

Has anyone who has fitted a Stiffy not ported their wastegate and having fitted the stiffy no longer has boost creep issues with or without an ESM chip?

Phil

[Dico]

I have just removed the cast iron piece of cr@p (which was a job and a half, with the engine out!)
The stiffy is being sent away next week to be ceramic coated.
My question is - Could porting the wastegate to 20mm have any negative effect? (should i just do it to be on the safe side)

Think i'll post this in my project thread (also)as we're a little off topic

[nitroman]

I think ( having actually looked at everything apart and the squared area of each part) that porting the waste-gate is your best bet in any circumstance, as that changes the ratio of exhaust going through the waste-gate and NOT turning the turbo. However the argument could be made that if your exhaust is soooooo efficient, the gas will be SUCKED out of the itty-bitty hole as the gate-aperture starts to open. I am somewhat skeptical of this myself.

[pjohn151]

That is exactly what I was trying to get across...
Boost is controllable through the ecu. Over boost/boost creep is not.

Phil