OMFG the TGP Crossovers SUCK!

[RedZMonte]

I got bored w/ took the heat shields off my spare DOHC x-over and the X-over I am modifing for Malibuolds. lets say there is a HUGE difference in the quality between the DOHC and the TGP x-over! seeing how there is only .3L difference in displacement... (pics tomorrow)

 

3.4L DOHC X-Over

* 2.25"

* Mandrel bent

* Single flex in center of the X-over (none of which i have ever seen/heard of cracking 3" long)

 

3.1L Turbo X-Over

* 1.75"

* Pressbent (Horribly Pressbent)

* 2 flexes that crack and leak (3" long ea)

 

The flexes look to be the same design as the one another.. I wonder why they DOHC flexes don't crack? My only thought is becuase the trubo generates more heat and maybe the heat is to much for thoes stock flexes...

 

RedZ

[GnatGoSplat]

Yep, it's the heat.

I could be wrong, but I don't think you'd want a 2.25" crossover on a TGP anyway. Exhaust velocity between the combustion chamber and turbo is very important and a larger crossover could decrease the velocity.

[RedZMonte]

I looked and if i keep the X-over in stock location by removing the heatshield i may be able to snake a 3" mandrel bent Downpipe. I removed the heat shield from the pipe and it cleared up a good amount of space. the Cercumference of the pipe went from 12" around to 8" around. If i tuck it up next to the motor as tight as possible and jet coat it. i won't need a heat shield and i should have enough room to get a 3" DP in there.

 

I was only planning on doing a 2.5" DP but now that i can free up some room i think it would be sweet doing a 3" that should help spool up.

 

RedZ

[RedZMonte]

Yep, it's the heat.

I could be wrong, but I don't think you'd want a 2.25" crossover on a TGP anyway. Exhaust velocity between the combustion chamber and turbo is very important and a larger crossover could decrease the velocity.

 

I agree a 3.1L w/ a 2.25" x-over would be a bit much. they should have aleast done a mandrel bent. that alone will improve gas velocity. If my name where McClaren i would have done a 2" mandrel bent x-over and a BIG T28 Turbo on low boost (better efficiency so it takes less boost to make the same power)

 

Shane

[Jeff M]

The OEM pipe is yet another of GM’s (self pro)claim to fame. GM is notorious for sending an item to be made out for bids, taking the lowest bidder and then telling them to drop the price more or they won’t do business with them, the suppliers have little choice. When I lived in MI I heard this a lot from Tier 1 suppliers to GM, enough now that I even see it written in publications and national magazines. And then there is the gouging on prices GM does, an example is a part on the Syclones and Typhoons, GM drilled down the price from the supplier to $7 on that item, then turn around and sell it for $180 when it was available (no more). So you can thank GM for that wonderful low bid piece of work X-Over pipe, not McLaren, their items they spec’d were the Garrett water cooled turbo, Blackstone intercooler, Blackstone bad-boy 3-core radiator and more, all of which GM again charges huge amounts for (those still available). As for turbo size, many OEMs spec a turbo small, to get the boost response to make for a nice drivable ramp of power, and GM felt that 2 seconds off the et of their normally aspirated GP was good enough to boost their GP sales, the TGP was more an image builder like the Syclone and Typhoon was to the GMC Sport Truck image, I like those images and drive one of each :-).

 

Jeff M