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Thought I'd share my build with everyone - it's a single turbo 6.0L L98 with 9.4 - 1 comp ratio. Has not yet been run I will be priming the engine up this week and putting it on the dyno. Current specs are:
Standard L98 Block torque plate honed to 4.010
Full ARP Studs and Bolts Throughout (Main + Head + Cam + Balancer)
JE FSR Pistons -16cc Dish w/ full stainless ring set
Compstar Rods 6.125 w/ARP 2000 Bolts
PAC 1218 Valve Springs 241 Heads w/ Ported Exhaust
Crane Tie Bar Lifters
Mellings HV Oil Pump
Aeroflow Sump Baffle
Precision CEA 6870 Gen 2 Single Turbo
3.5' Dump and Exhaust with 2.5' Cooler Piping
Walbro 450 Fuel Pump Intank
Powerbond Race Balancer
1000cc Injectors, Aeroflow Billet Rails
60mm External Wastegate
Custom grind 224/227 .115LSA Cam
Full Manual TH400 w/ 3500 Converter
FMIC also had a crane trunion rocker kit through it.
What are peoples thoughts on the 6870 single turbo setup on this engine? What power can I expect at 15psi on pump fuel? Keep in mind this build was purely for street use to I wanted a fast spooling punchy set up.
Happy for peoples recommendations and criticism. Happy to answer any questions too. Thanks.
Have you consulted a compressor map? Idk if that turbo will be efficient with that displacement..if it'll even make 15psi.
I have a GT4088R, which on a cammed SBE LS1, it makes a max of 11 psi. I just cranked my boost control up all the way, and that's what it'll max out at. This turbo has a 64.5mm compressor.
It spools very fast and makes great power for the street, and so far i'm happy.
Exhaust consists of a set of manifolds, 3" DP transitioning to a 3.5" exhaust with recirculated wastegates.
Have you consulted a compressor map? Idk if that turbo will be efficient with that displacement..if it'll even make 15psi.
I have a GT4088R, which on a cammed SBE LS1, it makes a max of 11 psi. I just cranked my boost control up all the way, and that's what it'll max out at. This turbo has a 64.5mm compressor.
It spools very fast and makes great power for the street, and so far i'm happy.
Exhaust consists of a set of manifolds, 3" DP transitioning to a 3.5" exhaust with recirculated wastegates.
Hey mate, the GT4088R flows at 75LB per minute and while Precision dont release compressor maps for their turbos the 6870 Gen 2 flows at 110LB per min according to them and its efficiency range is at around 28-30psi. I'm hoping at around 15-18 psi I can make my power goal. I'm not 100: sure though.
Hey mate, the GT4088R flows at 75LB per minute and while Precision dont release compressor maps for their turbos the 6870 Gen 2 flows at 110LB per min according to them and its efficiency range is at around 28-30psi. I'm hoping at around 15-18 psi I can make my power goal. I'm not 100: sure though.
I was not aware that they flowed that amount. Good Luck and keep us updated!
9.4:1 and 15 psi will be fine on 98 PULP. you should still be able to get conservatively 10-13 degrees is that without issue and a good safety margin from being on the limits of rattle
6.0 displacement is quite a lot to jam through a single T4 housing with 70mm wheel. plus side to that is it will spool pretty fast if you have an electronic boost controller to not send signal to the gate until 3-4PSI short of the target boost.
single 450 will limit your power and give you no option to move over to E85.
if you start with something low like 7psi boost and add 1-1.5 psi per power run you'll see where the turbine is starting to choke. when the turbine side is choking you'll easily see it. if its on its flow limits when comparing the graph with the previous one on 1-1.5psi less you'll see the peak power RPM point become lower and the graph will roll over harder in higher RPM.
you'll be able to find your happy medium to suit your application. for example you might personally be happy to be on 15psi beyond the turbine flow capability of the combo but cap your revs at 6000rpm to avoid running the engine where its choked up potentially causing damage from excessive back pressure. someone else may prefer to spin it to 7000rpm but drop the boost to 11psi to allow full RPM range without it choking up.
Okay guys. Got this on the dyno finally. Was a bit worried about the turbo size and that it wasn't going to flow enough air but boy was I wrong! The turbo was a perfect fit for this combo. The only issue we ran into was that my fuel pump (Walbro 460) maxed out way to early and was sucking it dry before 6000 rpm.
The car made 451rwkw @ 5800 rpm and 1200nm torque then ran out of fuel pump. Also with ZERO timing on 13 psi. Should see around 520-550rwkw safe with a surge tank, fuel pump and putting up to around 6800rpm with a bit of timing.
I'm over the moon with my result now knowing it's just a fuel pump in the way of hitting good power. The turbo had PLENTY left in it was barely in its efficiency range. It comes on boost with my converter at 3500rpm very hard which is what I wanted. I'd recommend this turbo for anyone building a street car. The motor was loving the boost it spiked a couple of times to 16psi (gate pressure) with no issues.
Will keep you posted when new fuel system is done.
Great result, get some more pump in it asap and wind it up. Agree with the above though, definitely put SOME timing in it, your EGTs must be through the roof.
Why the 241 heads? Did you only get the bottom end from the L98?
07-22-2018, 08:29 AM
Single PTE 6870 Gen 2 L98 Build 
