Suprdave

I think the twin scroll 7670 with the biggest AR would be awesome on a F20, Id go 8374 if it was a 2.2 with the 1.0.

Alloy Craft

7163 is still your best bet, IMO. it may run short of breath at red line but that doesn't matter since you will be spending very little time there anyway. For a street car you want boost ASAP. A larger turbo will be a little more efficient at your max HP numbers at the expense of spool time. I am running a 2.4 stroker with the 7064 and I can hardly notice the drop off up top. I made 425 whp at 16 PSI and 450 at 19, my dyno is below.

stena

wow.. you all got me worried.. i even mailed geoff asking for his opinion.. the turbo (7163 V) hasnt shipped yet they are waiting on the Inlet Vband ring ..
I asked if i can change it they said no problem.. they have a 8374 Twin no WG and T3 single with IWG on stock..no Twin with IWG,, my manifold construction is almost done and its possible to make it a Twin if i want since the connection part to the turbo isnt done..
I got worried that due to high efficiency head the 7163 would be smallish..but Alloy Craft put some confidence i did the right choice originaly..
anyway
1. My car is and will be a street engine.. my target is 1 bar 400-500hp..
2. I chose the 7163 because of the tech in it (alu bearing housing and mixflow turbine) and Vband so i position the turbo just perfect for my Airfilter and Intercooler and not be restricted with the 4 bolts a T4/T3 would
3. i will build a 2.4L engine in the future..and will have it but probably run it after my 2L fails..
4. if i go bigger (8374) many tuners said Twin isnt needed on our Engines but Geoff suggested i go with EWG and a twin WG
5, i Hate the fact i cant get the 8374 In alu bearing housing and move 5 lbs of its weight on the Header..

so shoot.
should i stick with my original decision or get the bigger and have the room to grow and sacrifice low end..

stena

some progress fotos..sorry for the crappy fotos..,not my phone


http://1drv.ms/1S4EBkY

ninetysixyenko

14-15psi target with 400-500whp? I'd get the 7670 with .92 IWG hands down. I'm at that target boost and make higher 400s, and I have 10psi by VTEC crossover, and the rest comes very shortly after.

I agree with alloycraft that the 8374 is to big for what you want. I think the 7163 will leave you desiring more. The 7670 will get you where you want to be, and be capable of much more on e85.

stena

Can u post the dyno and boost map?

stena

well you dot want to be in my shoes now..
i was so happy with the 7163 as a choice and worried that it might be a problem controlling the boost at low Rpm and Vtec spike with the IWG..
and now i am drawn to the 8374 since everybody is saying that its a perfect match for the high flow head/engine our car has and with it i will avoid the boost spikes and possible control problems on low rpm. .. i dont know what to do.. really... go the easy route and wait for boost at higher rpm and not choke our high flow engine ..or go the smaller high speed 7163..? i changed my mind today 3 times..to mail or not to mail and ask for a change of turbo..
Personaly i think that 7163 is a better turbo choice than the 7670..
thanks for all the input so far and thanks to geoff for the free advice i got.
stefce

stena

seen this and i see it starts to make boost/power after 4000rpm..
https://www.youtube.com/watch?v=hsvR5CUjYes
i will probably go with T3 single 8374 IWG ..its 0.83AR and i dont know if get much benefit over it with the Twin EWG 0.92AR

ninetysixyenko

The manifold you use will change things a lot as well, a forward facing/side winder/long runner will build boost slower but flow better up top. A log manifold/ramhorn will build boost very quick but not flow well up top.

ninetysixyenko

This is on waste gate with max preload, with no boost controller. made about 13PSI. VTEC crossover was and is at 4800. the lower me moved the crossover point, the earlier the TQ curve spiked. I opted for 4800, because doing 80 on the highway cruising it sits at 4400. you can also see it running out of steam after 8500 (~10 PSI). When tuning was complete, boost controller duty stayed in 20s from 4500-7500 to make 15PSI, then we needed 100% duty to maintain that 15PSI until redline, and it still fell to 13.5PSI after 8500.