New turbo garrett GT 25/30r turbo setup

[gldgti]

Looks nice marty, seems that you've ended up with a good thing there. what thickness tube have you used? and, where you've butt-joined the tube, what was your weld process? i'm guessing for the application its thicker than 2.4mm? in which case you should have been able to weld it and be confident of not blowing through/making oxide 'bubbles' on the inside of the weld? i've had trouble with this before on 1.6mm tube.

[tommymac]

curious to see the dyno sheet when you get one

[POLARBEAR666]

I had a GT25/40R in my old subaru before upgrading to a GT30/40. The 30/40 made more power justabout everywhere and spooled earlier. The GT25 in my spec was a dog of a turbo.

I would sell that GT25 and then get a GT3040, flanges would be an easy change or u can buy adaptors. Then just fit an external gate...That will give a much better screamer pipe effect as it won't have boost creep and leaking issues at higher boost pressures.

I used a Zage wastegate that was only $300 but worked perfectly.

Also, make sure you fit some high lift camshafts if you an afford it. That will make your engine feel much stronger at higher revs but before boost comes in and up top your power curve will be like table mountain.

honestly, changing to GT3040 with external gate was a 200% improvement on my subaru over the GT25. I went from 250kw and 420nm @ wheels to 300kw and 530nm @ wheels.

Here is my 3040 in position

[twin eng, twin turbs]

Looks nice marty, seems that you've ended up with a good thing there. what thickness tube have you used? and, where you've butt-joined the tube, what was your weld process? i'm guessing for the application its thicker than 2.4mm? in which case you should have been able to weld it and be confident of not blowing through/making oxide 'bubbles' on the inside of the weld? i've had trouble with this before on 1.6mm tube.

Thanks gldgti, i used 1 1/4" internal diameter tubing through out the manifold with 3mm wall thickness. I linished a 45 degree weld preperation on each butt joint and once welded linished the outside and inside before going onto the next joint. Using an old brake cylinder hone with the flexible shaft i made a collet lock on the end so i can port and polish around corners up to 200mm inside with either a burr or flapper wheels. This works well so weld protrusions are easily fixed.

I'll be facing the sealing faces tomorrow, pics soon...

[Mrk_Mickey]

VERY cool work there mate, didn't read this thread until now. Some amazing pipework which I hope to be able to do myself some day

[gldgti]

Thanks gldgti, i used 1 1/4" internal diameter tubing through out the manifold with 3mm wall thickness. I linished a 45 degree weld preperation on each butt joint and once welded linished the outside and inside before going onto the next joint. Using an old brake cylinder hone with the flexible shaft i made a collet lock on the end so i can port and polish around corners up to 200mm inside with either a burr or flapper wheels. This works well so weld protrusions are easily fixed.

I'll be facing the sealing faces tomorrow, pics soon...

just noticed too - good to see the pipes coming together in the right order! i picked up a set of 4AG headers yesterday and noticed that the order of the header pipes coming together in the 4-1 collector was wrong....

[Preen59]

just noticed too - good to see the pipes coming together in the right order! i picked up a set of 4AG headers yesterday and noticed that the order of the header pipes coming together in the 4-1 collector was wrong....

"Radial Firing Order".

[twin eng, twin turbs]

Yes the correct firing order as the pipes merge from 4 into 1 is worth a few extra kw's, good extractors are designed this way to draw the gas from the previous cylinder out for a fresh inlet charge.

The manifold is almost done now, i machined both flange faces to ensure a good seal is obtained but only photographed one. I have welded in "webbing" between the pipes to ensure that it dosn't warp under the high temperatures associated with the turbo. The last manifold glowed red hot at the collector at night after a run up the local drag strip! Im expecting this one to do the same.. The collectors flange is now weld filled behind and linished back with threads drilled and tapped for studs.

Ill port and polish it tomorrow and check the port matching..

[Golf Loon]

Best thread on here, keep up the good work and the updates mate.

[Jarred]

looks cool marty.

could you, or anyone explain the radial firing order deal. like, how it's done, and what is actually done?

thanks

[twin eng, twin turbs]

Best thread on here, keep up the good work and the updates mate.

Will do Matt, just wait till i start the scirocco thread...

[Mrk_Mickey]

I've used a mill before! I know what it is, I feel so special...

Great work! I'm keen to gain that knowledge that Jarred wants too

[twin eng, twin turbs]

looks cool marty.

could you, or anyone explain the radial firing order deal. like, how it's done, and what is actually done?

thanks

If you check the pics out on the bottom of page 3 showing all the pipes merging into the collector you can see they merge in the firing order of the engine 1,3,4,2 going around the collector. This creates a spiraling effect on the exhaust gas. When an exhaust pulse comes from one cylinder another pulse wave is sent down the previous exhaust runner drawing the exhaust gases out of it allowing for a less contaminated inlet charge of fresh air and fuel.
It gets very techinal on tuned length runners as the length is determined by various different elements of engine design but not to go into to much detail the compression, inlet manifold length, cam profile lift, duration and overlap....

[Jarred]

cool thanks marty. now at least I understand what you're talking about!

[twin eng, twin turbs]

I ported, polished and port matched the exhaust runners to the head the sarvo. Ill do the collector tomorrow and make a supporting mount up from the gearbox aswell.