Hi Geoff,

I’m going to have a play around with the matchbot again. The last time I looked at it I found it difficult to use but I’m sure the tutorial will help a bunch so thanks for the vid!

I see you are recommending the 8374 for Time Attack and I'm interest to hear how Emp preferred the 8374. I was actually thinking of going for its baby brother the 7670 for my Time Attack build. My engine is a Long Rod 2.0L (as opposed to Sierra-Sierras 2.2L) and I'm hoping to have a long, useable powerband that tops out at 9500ish.

I've had some help on these calcs (cheers AndyF_RSX off the MLR)

Mass of air (g/s) = rpm/60 * displacement (l) / 2 * volumetric efficiency * air density (g/l)

Displacement = 2 litres
Target rev limit = 9,500 rpm
Volumetric Efficiency = 85%
Air density = 3.5 g/l (Lets say I plan on running 2 bar with an intake temp of 25°C)
Mass of air = 9500/60 * 2/2 * 0.85 * 3.5 = 471 g/s
Which converts to 28.263 kg/min = 62.18 lbs/min

If my VE was closer to 100% I’m hoping to get closer to 100% with a CNC ported head and a good set of cams (Jun 272’s).
So reworking the calc:
Mass of air = 9500/60 *2/2 * 1 * 3.5 = 554 g/s = 73 lbs/min

So according to those calcs and depending my actual VE figure, I should be looking for a turbo that flows 62-73 lbs/min? Which is why I was looking at the 7670 rather than the 8374.

What do you think would be the best match for me?

Thanks for your help in advance.

Cheers,

Karl

 

I too am building a LR2.0L for my 2g Eclipse GSX.
1.05 A/R T4 EFR7670
JMF T4 TS Exhaust Manifold
GSC S2 cams
Curt Brown Spec 2g Head
Curt Brown Spec 2g JMF Drag SMIM
Shooting for 500 to the ground.
Should be a beast from 3500rpm up to 8500rpm no problem!

 

Hi Karl, 62-73lb/min is the turbo size most people build their evos to utilize. A GT35R is in that area, fp black of course, some hta turbos, precision 62, etc most all of them are in that range. The EFR 7670 is basically designed to give the same top end power as a gt35R but with much more bottom end... so yes I agree the 7670 would be a great starting point for a track evo build. The S200SX 7570 is actually the precursor to the EFR 7670 and they share almost identical turbine wheel geometry, so its also an option worth considering.

i realize VE is a grey area, but one important thing to realize is that VE is not static and changes with RPM. For example, if you had a built 2.0 and intake mani/mildly ported head with good valvejob and some 272s, your expected VE curve might be something like this:

idle 80
2000rpm 83
2500rpm 87
3000rpm 92
3500rpm 95
4000rpm 100
4500rpm 103
5028rpm 106
6000rpm 107
7000rpm 107
7500rpm 105
8000rpm 103
8300rpm 101


the 8374 is definitely a high power turbo - making 700ftlbs tq at 5000rpm is unreal, according to Eric Hsu of Cosworth, the emp says this is one of the scariest fastest cars he's driven, and hes been seen shaking when he gets out of it

that powerband from 3500 to 8500 will be very very broad... you should definitely be able to reach those goals

 

Kins, if you're serious about spinning out to 9500 RPM, then you'd probably want the 8374, not the 7670. From what I can surmise, the 8374 would give you an effective power band of 4500-9500 RPM. With some tweaking it might spool a little sooner. Looking at the compressor map, I don't see the 7670 being all that effective past 8500 RPM, but the fun begins in the mid 3K RPM range - so a similar effective powerband. I did my calculations based on a target boost of 30psi and a 2.0L. I could go for an 8374 and rev my engine out to 9500 (it's been built and could handle it), but I will most likely opt for the 7670 because:

1. I want my car to remain streetable - hopefully be even more streetable than it is now

2. I don't plan on boosting much past 30psi, limiting how much I will gain from the 8374

3. and the engine should also last a little longer by not revving it out quite as far ... although it _is_ nice to have the extra revs on tap for those tracks where I can save a shift or two by holding onto whatever gear I'm in before the next turn.

l8r)

 

Geoff,

How confident are you that on a reasonably well prepped 2.0L with the proper supporting mods, and using a Full Race manifold, downpipe and midpipe, the 7670 will be able to exceed 600 HP? I'm looking at the compressor map and had some question whether it can flow enough air within a reasonable efficiency range to make that level...

 

^ I agree. 600HP, yes. 600 whp, IMO going to be a stretch on a 7670.

l8r)

 

I hope that the 7670 can hit 14psi at 3500-3800...on a 2.2L CR 8.8:1
480whp 22psi and hold it upto 6500rpm.

That is lots of power for a 2200lbs circuit car

 

Don't know much about these turbo's

How would a 8374 do on a long rod 2.4 looking to achieve somewhere in the 700's for power?

I'm looking for more info on BW turbo's.

 

good choice. the 8374 is what geoff recommended to me and i told him i want a responsive 750whp.

these are ROUGH equivalents
7670=35r
8374=hta86
9180=hta37r

 

Check out the link below.

http://www.full-race.com/articles/bo...fr-turbos.html

Regards
Jon

 

Are you guy going to packaging these turbo's in a kit (Mani and DP?)

And thanks for the link.

I'd love to see a comparison to the HTA86 and 6262.

 

this powerband is what the 7670 turbo was designed to do (and why Im using it on my personal evo project). In fact, the standard S200SX reaches your targets on only a 2.0L, so with your 2.2L the EFR should perform even better

The 7670's compressor map shows maximum airflow rate is 64lb/min (just before choke flow). This is close to the same as a standard garrett gt35R - so whatever your engine setup does with a gt35R for peak power will be similar to the 7670 peak power (a tiny bit less). The big difference of course would be the response, spoolup and area-under-the-curve powerband - with similar top end

The 8374 is slotted right at 700+whp. What Long rod 2.4 are you thinking - 94mm stroke and 156mm rod?

yes the EFR turbos are plug-and-play for our current twinscroll evo turbos kits, same kit

 

Stroke and bore diameter determines displacement.

94mm stroke in a 4G64 will yield ~2.2L.
Get some 159mm rods and pistons with a compression height of 29mm.
That will give the user a 2.2L with a rod/stroke ratio of 1.69.

 

sorry im confusing the setups - what is the block, stroke and rod length?

 

generally lr 2.4L is 100mm stroke and 156mm rod in a 4g64 block, correct? that sure doesnt leave much compression height. heck, if they can make a really strong piston with that compression height i might as well sell my 156mm rods for my 2.2L and get 162mm rods.