FK8 turbo selection question

[Potato]

Hi I am a newbie and I was looking for a turbo upgrade for my FK8, and I do have some questions.
So basically, I just need a better turbo with improved lag and spool, and HP is not my first target. Budget is not a big problem here.
Should I go for MHI Stage 2 in this situation?
I found this turbo a journal bearing turbo, so maybe I should go for ball bearing turbo? Sth like PRL700? I was told ball bearing turbo is better in lag and spool area.
Really appreciate for any suggestions from your guys.

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[Builtfc1]

Rv6 r660 is what you want

 

[AlphaDigital]

Hi I am a newbie and I was looking for a turbo upgrade for my FK8, and I do have some questions.
So basically, I just need a better turbo with improved lag and spool, and HP is not my first target. Budget is not a big problem here.
Should I go for MHI Stage 2 in this situation?
I found this turbo a journal bearing turbo, so maybe I should go for ball bearing turbo? Sth like PRL700? I was told ball bearing turbo is better in lag and spool area.
Really appreciate for any suggestions from your guys.

The turbo you choose should suit the type of driving you want to do and the power goals you want to meet. You may find yourself severely disappointed if you just choose a random turbo out of the handful that are available for the car.

If HP isnt your first target what is? You wont find a better turbo in terms of response, spool/lag time. The factory turbo is fine for those.

As you go up in size, youll actually find that your spool times may be longer with increased lag, which is normal because youre not requiring more air to move the larger wheels on the turbo. While this may be minimal with the MHI, youll definitely notice it on a P600/P700 turbo.

Its all a balancing act. What you gain from a larger turbo will also cause you to lose in some benefits that a small turbo gave you.

 

[shadow]

MHI Stage 2 has about a 500 rpm lag.

 

[speedyserg]

Define your hp goals and go from there
After that decide on budget
Once you narrow your hp and budget down the turbo will select itself of the available options.

Beyond turbo selection - spool is effected by the head, cams, intercooler, charge pipes and ignition timing....they all work as a system.

I didn't care for the stock turbos response on ethanol as it tends to overload the tires - makes midcorner adjustments a little dicey.

The larger turbos give you much more peddle travel before power comes on - allows you to dial in your line more accurately without washing out from loss of traction. Once the straight sections come, the top end of the larger turbo helps alot as well.

For autocross it's slightly tougher as throttle inputs tend to be more on/off vs long highspeed sweepers where mid corner corrections happen so the stock turbo does decent if you can hook. Response matters when the runs are less than a minute for full courses vs an open track where it's 2 to 4 minutes long.

Another factor folks forget is canyon carving - especially downhill runs, tend to create alot of engine braking/backpressue build up - the stock turbo chokes quickly and can end up sending backpressure back into the motor and crack rocker arms etc. Alot of guys don't brake hard enough and end up downshifting at speeds that zing the motor past 8k on stock valvetrain....horrible idea. Again - the larger drop ins reduce the chance of that backpressure build up that can further strain the valvetrain - cant fix rookie mistakes like proper braking, heel/toe, rev match etc ....

I liked my p600 and fell in love with my R660....car feels more old school with that high rpm rush of old vtec. P600 dies off past 6800 so moving to the r660 and carrying power to 8200 is more my goal. If you want 500ftlbs at 2500rpm - get a v8

Honestly these drop ins are pretty good and spool easily by 4k rpm if you want - it's just safer to bring in full boost later so you don't bend/snap a stock rod.

Again - hp goals/use and then budget.....that will narrow your choices significantly

 

[Learn2turn:)]

" Another factor folks forget is canyon carving - especially downhill runs, tend to create alot of engine braking/backpressue build up - the stock turbo chokes quickly and can end up sending backpressure back into the motor and crack rocker arms etc. Alot of guys don't brake hard enough and end up downshifting at speeds that zing the motor past 8k on stock valvetrain....horrible idea. Again - the larger drop ins reduce the chance of that backpressure build up that can further strain the valvetrain - cant fix rookie mistakes like proper braking, heel/toe, rev match etc .... "

Another excellent point Serg!

 

[Potato]

Define your hp goals and go from there
After that decide on budget
Once you narrow your hp and budget down the turbo will select itself of the available options.

Beyond turbo selection - spool is effected by the head, cams, intercooler, charge pipes and ignition timing....they all work as a system.

I didn't care for the stock turbos response on ethanol as it tends to overload the tires - makes midcorner adjustments a little dicey.

The larger turbos give you much more peddle travel before power comes on - allows you to dial in your line more accurately without washing out from loss of traction. Once the straight sections come, the top end of the larger turbo helps alot as well.

For autocross it's slightly tougher as throttle inputs tend to be more on/off vs long highspeed sweepers where mid corner corrections happen so the stock turbo does decent if you can hook. Response matters when the runs are less than a minute for full courses vs an open track where it's 2 to 4 minutes long.

Another factor folks forget is canyon carving - especially downhill runs, tend to create alot of engine braking/backpressue build up - the stock turbo chokes quickly and can end up sending backpressure back into the motor and crack rocker arms etc. Alot of guys don't brake hard enough and end up downshifting at speeds that zing the motor past 8k on stock valvetrain....horrible idea. Again - the larger drop ins reduce the chance of that backpressure build up that can further strain the valvetrain - cant fix rookie mistakes like proper braking, heel/toe, rev match etc ....

I liked my p600 and fell in love with my R660....car feels more old school with that high rpm rush of old vtec. P600 dies off past 6800 so moving to the r660 and carrying power to 8200 is more my goal. If you want 500ftlbs at 2500rpm - get a v8

Honestly these drop ins are pretty good and spool easily by 4k rpm if you want - it's just safer to bring in full boost later so you don't bend/snap a stock rod.

Again - hp goals/use and then budget.....that will narrow your choices significantly

Thank you so much for your professional suggestion!
So my target HP is around 500, and 100% daily street driving.
I found that spoon big turbo is expensive, but compare to MHI stage 2 I dont see any special about this turbo, anyone tried this turbo?

 

[Typer27]

Thank you so much for your professional suggestion!
So my target HP is around 500, and 100% daily street driving.
I found that spoon big turbo is expensive, but compare to MHI stage 2 I dont see any special about this turbo, anyone tried this turbo?

If you order from https://www.blackhawkjapan.com/products/spoon-18900-fk8-000?_pos=79&_sid=f7d06c71b&_ss=r

It should be cheaper, but I believe it is just an MHI Stage 2 with titanium bits and Spoon plate. One member does have it. I think it's Z06Chris? I could be wrong.

 

[ToofHurts]

Full Race is MHI turbo for $2,000. Black Friday deal.

 

[Potato]

If you order from https://www.blackhawkjapan.com/products/spoon-18900-fk8-000?_pos=79&_sid=f7d06c71b&_ss=r

It should be cheaper, but I believe it is just an MHI Stage 2 with titanium bits and Spoon plate. One member does have it. I think it's Z06Chris? I could be wrong.

Oh this price looks more reasonable, thanks for the information!
So MHI stage 2 turbo is journal bearing, I think there might be someone try to change it to a ball bearing, I knew someone did this to the OEM turbo.

 

[speedyserg]

The MHI spools quickly- wouldnt get hung up on it being journal bearing or not.

All of the drop ins will spool slower than stock which again - is not a bad thing when your making 500+whp/430+wtq -

To extract 500 from an MHI you'll need ethanol/meth and upgraded hpfp/lpfp

Typically about 3000 to 5000 for fuel and 2000 to 3000 for the turbo plus install.

500whp is pretty easy to hit and keep things simple. I really enjoyed stock exhaust 550ish whp .....great sweet spot for the car/budget

 

[xdecemberguy]

P600 still is the sweet spot. 9 blade instead of 5, ball bearing-not journal, quick spooling. Bigger Compressor wheel 54mm/67mm compared to MHI 51mm/65mm, and Turbine 54mm/49 compared to 52mm/47mm. Great power pick up from about 3,000 rpm to about 6,000. Just under 500 hp with Ethanol, with pump gas (93) just over 400hp. Good numbers for stock motor. Sounds great. Now if you add ported manifold, TR2 cams, and 2000 cc fuel injectors and have a 3inch exhaust..who knows..

 

[speedyserg]

P600 still is the sweet spot. 9 blade instead of 5, ball bearing-not journal, quick spooling. Bigger Compressor wheel 54mm/67mm compared to MHI 51mm/65mm, and Turbine 54mm/49 compared to 52mm/47mm. Great power pick up from about 3,000 rpm to about 6,000. Just under 500 hp with Ethanol, with pump gas (93) just over 400hp. Good numbers for stock motor. Sounds great. Now if you add ported manifold, TR2 cams, and 2000 cc fuel injectors and have a 3inch exhaust..who knows..

The turbo hotside is too small and creates a bunch of backpressure above 6500
I made 547whp with my p600 on e50. The hotside is too small really for much past that which is why RV6 went with a larger hotside.

Prl tried to fix this by using a larger cold side wheel to move more air at slower shaft speeds but the back pressure issue is still there as they kept the hotside largely the same - the made the wastegate hole a little larger to combat the backpressure but above 7000 is still is an issue.

When they tested the p700 on the built motor with cams they made 640ish at 7000 and hit a wall by 8000rpm and only 600whp. Using a BMEP sensor they could see the backpressure ratio climbing past 2:1 past 7000.

I had a v2 p600 which didn't really give me any issues and sounded great. But personally I wanted power to climb past 8000. That's a major reason I agreed to test the RV6 R660.

The RV6 uses a 54/67 cold side with a 54/49 hotside ....wait but isn't that the same as the p600? Yup - what's different? The exhaust housing. The RV6 hotside housing is visibly about double the size and is a 0.81 AR.

It's the largest hotside RV6 could fit in the stock location which is how I was able to flow 600whp with it on stock cams and stock bottom end at 32.5psi. The TR2s should be able to bump peak to whatever threshold the turbo can flow....my hope is 640whp but I don't know if there is enough wheel to make it happen. The built motor setup used a p700 setup which uses 58/71 wheel aka 4mm larger on both measurements. On top of the larger wheel the built motor also ran 35psi (motec ecu) to hit 640/510.

I don't think a p600 would be able to hit those number as the wheel is smaller and uses the same hotside.

The smaller hotside turbos like the p600 and MHI spool pretty quick but it's not like the RV6 is laggy - on my ported head it damn near spools like stock so I have to be more careful with it vs a stock head but the upside of a touch of lag is the thing breathes to 8000+ and widens the usable powerband.

Again this is where the use of the car becomes important - leaving the motor alone vs beefing it up little by little etc

It's quite a rabbit hole and the path isn't very straight unless you have clear goals and stick to them. Few people stick to their original plan if they even have one tho

Cheers

 

[Potato]

Define your hp goals and go from there
After that decide on budget
Once you narrow your hp and budget down the turbo will select itself of the available options.

Beyond turbo selection - spool is effected by the head, cams, intercooler, charge pipes and ignition timing....they all work as a system.

I didn't care for the stock turbos response on ethanol as it tends to overload the tires - makes midcorner adjustments a little dicey.

The larger turbos give you much more peddle travel before power comes on - allows you to dial in your line more accurately without washing out from loss of traction. Once the straight sections come, the top end of the larger turbo helps alot as well.

For autocross it's slightly tougher as throttle inputs tend to be more on/off vs long highspeed sweepers where mid corner corrections happen so the stock turbo does decent if you can hook. Response matters when the runs are less than a minute for full courses vs an open track where it's 2 to 4 minutes long.

Another factor folks forget is canyon carving - especially downhill runs, tend to create alot of engine braking/backpressue build up - the stock turbo chokes quickly and can end up sending backpressure back into the motor and crack rocker arms etc. Alot of guys don't brake hard enough and end up downshifting at speeds that zing the motor past 8k on stock valvetrain....horrible idea. Again - the larger drop ins reduce the chance of that backpressure build up that can further strain the valvetrain - cant fix rookie mistakes like proper braking, heel/toe, rev match etc ....

I liked my p600 and fell in love with my R660....car feels more old school with that high rpm rush of old vtec. P600 dies off past 6800 so moving to the r660 and carrying power to 8200 is more my goal. If you want 500ftlbs at 2500rpm - get a v8

Honestly these drop ins are pretty good and spool easily by 4k rpm if you want - it's just safer to bring in full boost later so you don't bend/snap a stock rod.

Again - hp goals/use and then budget.....that will narrow your choices significantly

Thanks for the information, that is really helpful.
Btw, may I ask if I have hondata fuel system+93+intake(maybe PRL)+rv660+tuning, what is the proper hp I could ecpect? 500? And IDK for hp>500 do I need to upgrade the k20 with some forged parts.

 

[speedyserg]

Thanks for the information, that is really helpful.
Btw, may I ask if I have hondata fuel system+93+intake(maybe PRL)+rv660+tuning, what is the proper hp I could ecpect? 500? And IDK for hp>500 do I need to upgrade the k20 with some forged parts.

On a bone stock motor you can safely make around 540ish depending on fuel and driving style. The biggest enemy is heat and cooking the headgasket.
Hondata pump with their injectors usually makes around 500ish-510whp or so on e50
On 93 I would imagine quite a bit lower maybe 430-450ish on 93. Tough to say but I'm sure others have already tuned on 93 with theirs on stock motors.

I cooked my headgasket as I'm pretty hard on the car with alot of long highspeed pulls in 5th and 6th so I upgraded my headgasket. Headstuds and the engine is happy at 600/490

Fuel wise I run ethanol for octane insurance - I don't trust pump 91 here - hopefully your 93 is consistent but our socal 91 is dog water.

As far as forged parts- probably around 700ish+ you should run forged pistons/rods but as long as your tuner brings the torque in above 4k you should be fine. Too low with too much torque is what bends/snaps rods. I bring in 32.5psi at 4400ish and peak torque is around 6000rpm ....it's alot but my motor is setup for the additional torque being made with the 625+ studs and JE pro seal gasket.

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