Headers?

Well I've got to chime in on this one. No header is going to make much more power at 3k on this engine. The engine itself isn't making much power and to increase exhaust velocity at that speed would require a tiny primary. A tiny primary will not make power in the upper rpm ranges, it will be way too restrictive. A good header will make more power in the midrange, but gobs more on the top end. If you look at the stock dyno curve, hp and torque fall off rapidly as rpm goes up. Our header with the stepper design increases midrange power without sacrificing top end at all.
If you don't plan on revving your motor above 4k, don't buy a performance exhaust.
I'm still waiting for someone to dyno their exhaust, whether a pieced-together factory system or an aftermarket system and post the results.
 
More Hp at All Tested RPM, What's Not to Like?

If you look at this dyno chart, the Allison header exhaust increases HP at ALL RPM's tested.

Dr. Jeff makes it sound like you lose power somewhere in the RPM band, but with this system you GAIN POWER at EVERY RPM!

What is not to like?

Nucleus

x19dynotestcomparison.jpg
 
Gotta agree with nucleus's point... plus at the 3000 or so point where the stock set up has already pretty much peaked torque wise, the header is ahead by a few ft/lbs, and still surging upwards... I'd think you're going to feel that. The torque peak is higher, but it's in a RPM range that I think most X1/9 owners use when driving their cars... I sure do.

This isn't miata.net with a bunch of 'I'd never rev it over 5000' owners is it?:nana:
 
For the third and final time

As I've stated clearly in each of my posts in this thread, my comments on engine modifications and exhaust system design were NOT about any specific system, brand, manufacturer, or seller.
The point I made was that every modification has trade-offs or compromises. I know that WYOX19's car is a very nice example of the X and wanted to assist him (per his request) in making an informed decision about any changes to it.
 
Dr.Jeff said:
As I've stated clearly in each of my posts in this thread, my comments on engine modifications and exhaust system design were NOT about any specific system, brand, manufacturer, or seller.
The point I made was that every modification has trade-offs or compromises. I know that WYOX19's car is a very nice example of the X and wanted to assist him (per his request) in making an informed decision about any changes to it.
Click to expand...

My point is that is no trade-off with the Allison exhaust system. More power at all RPMs.
 
Readily available

Readily available... well in my books one web search that turns up the required part means it is actually quite readily available, certainly not "unobtainium"

Lots on ebay too...not to suit the Yugo EFI specifically, but these would sure do the job...

http://www.ebay.it/itm/COLLETTORE-S..._automobili&hash=item35b89e8e55#ht_500wt_1180

http://www.ebay.it/itm/COLLETTORE-S...bi_Nautica&hash=item27c74fb3c7#ht_5322wt_1163

and front pipes from plenty of other Fiat models (or even a Yugo) would give you the basics of the front pipe setup too, then just needing to adapt to the existing CC and muffler.

http://www.ebay.it/itm/FIAT-128-COU..._automobili&hash=item336ddfdb3c#ht_500wt_1180

besides the ONLY reason to use theYugo EFI exhaust manifold would be to fit the O2 sensor into the manifold, it wouldn't be too difficult to fit the O2 sensor into the front pipe as an alternative, and then any carbed Yugo, 1974 x19, twin out 128 coupe which certainly are more readily available to the US market.

Bottom line is that this setup will yield the same (or better) results than any of the aftermarket "performance" units available...quite simply changing from a single out manifold and pipe to a twin out manifold and pipe is worth around 8HP, using factory dyno figures...which mirrors the result you would get using the previously mentioned "performance" system ... but for a fraction of the price, no if's or buts.

SteveC
 
You must log in or register to reply here.
Back
Top