https://www.rx7club.com/showthread.php?t=417756

I am new to this part of the forum but have been thinking of going single. I saw this kit in the classified section and thought it sounded like a great deal. But after talking to RotaryResurrection about it, and to other single turbo members, I'm not sure it is such a good deal anymore.

First, I'm concerned about the shaft play. RotaryResurrection said he rebuilt the turbo after he got it but it still had axial play from the shaft being worn so it is not snug in the new bearings. Will the life of the turbo be significantly reduced or is it not anything to worry about?

Also, RotaryResurrection told me that it had pretty quick spool up – about the same as non-seq. – and hit 10psi by 4200rpm. That doesn’t seem very fast to me (I run seq.), is that quick for a single of that size?
I have been reading as many threads on this single turbo section as I can and noticed that a divided turbine housing spools quicker than non-divided. So is that the reason for the slower spool up?

I also noticed that the exhaust manifold sits far ahead and up high compared to other single turbo setups. Is this custom manifold a good design?
It seems that is awful lengthy. Could that cause more lag?

Sorry for the long post. I still have more questions but I would like to get these answered first, as they are the ones that concern me the most.
I just don’t want to buy it and then end up with a lot of unusable junk.

 

kinda high in my opinion, though I am sure that Kevin would give you a lot of help with it though as he has a reasonably decent reputation in the circles.... I personally would ask kevin for all of the fittings/pipeing to the IC, along with new gaskets all around at a minimum at that price, but its all supply and demand.

Ken

 

He said he would include the custom IC pipes in the pics.
I thought it was high too. But he is pretty firm on the price.

 

Like I said he's got a good rep so if something was truly wrong I think he would tell you, but depending upon where you buy your parts from you would not be paying much more for new stuff,
figure a new turbo is about a grand flat depening upon what you buy, manifolds can be pricy, but the old tried and true cast HKS aree hard to beat at 400 or so, that only leaves the wastgate...

once again you have to decide if you want new or used you will save a couple on the used but its up to you.

kenn

 

Actually longer runners REDUCE lag, and improve turbo response.

 

Why? Would you mind elaborating this?

 

Yeah, that does not seem to make sense.
I would think shorter runners would have more velocity coming out of the engine and retain more heat for better spool up.

 

only 10psi by 4200rpm sounds lousy. however, i have no expericnce with on center or undivided. but i dont think they should adversely affect the spool that much.

my 60-1 w/P-trim, .84, divided, tangentail sees 15psi before 3900rpm on a large streetported low (8.5:1) comp engine. on a stock or mild ported 9.0:1 this would probly be around 3600rpm.

-2cents

justin

 

I wonder if I could find a divided turbine housing to replace the undivided one?
Maybe that would help.

 

yeah put a divided .84 and it will make a difference of about 600~1200 rpm depending upon ports, engine timing and some other odds and ends. but that would be another 200 dollars, and at that point and time it is for a fact cheaper to buy new..
ken

 

Search around, there are quite a few threads on this. The best way to explain is: blow on a pinwheel in short bursts, now blow in a long smooth burst, which one spins faster?

Also look at the piston manifolds, the runners are pretty long, and they seem to work pretty damn good.

 

Buying a divided turbine for that UN-DIVIDED manifold would be useless and hurt spool further. Not to mention this mani is built using a on-center housing, so once you put a tang housing on there the turbo and or the fabbed down pipe will most likely not clear the lower intake. Not to mention the DP would then need to be moded for the new position of the turbo and need a new connection (v-band) because the tnag housings do NOT come with those 4 bolt flanges like the on-center housings do.

~Mike.............

 

Thanks, I appreciate the useful answer.

It's starting to sound like it is not the setup I'm looking for. I guess I'll wait for something closer to what I want. This just sounded like a good deal, but now just seems like more of a pain in the a$$ when something goes wrong.

 

Wasen't detering you from buying the kit. Just pointing out that modding it will cost more money and work. I say to anyone looking at buying this to just buy it and run it as is at a good price or look for something different. FWIW, most with a non divided log manifold and .96 turbine are seeing these kinda spool times, maybe a bit better. Its the guys with large street ports and more expensive divided manifolds and turbines that are seeing spool times in the 3200~3800 realm. BTW, I vouch for Kevin @ RotaryResurrection, hes a good honest guy.

~Mike...........

 

a longer drawn out pipe does have higher velocity, it is just less flow, its kinda in the same way that longer runners give NA's more low end