Engine building for "Time Attack"
04-06-14, 02:38 PM
#1
Rotary Shack
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Engine building for "Time Attack"
Hey guys, so I'm interested in building a 13BT for "Enthusiast class" time attack and just wondering if I can get some feedback on what options I have at my disposal.
I have here posted the rules that stipulate what engine modifications are legal for this specific class.
I hope this thread can eventually act as a database for anyone interested in pursuing a "time attack" related build.
This is not and will not serve as my build thread, just hoping to get some discussion going. I'll most likely make a separate build thread.
----------------------------------------
16 ENTHUSIAST CLASS
The Enthusiast Class is designed to give street driven “grass roots” vehicle owners the ability to compete with basic bolt on modifications.
16-1 Engine and Drive Train
16-1.1 Engine must be OEM for particular make and model. No Engine swaps. Engine replacement is allowed ONLY from OEM engine from original make and model. Japan/European engine replacement is allowed as OEM factory trim. Drive wheel configuration changes are not permitted.
16-1.2 Vehicles using factory OEM forced induction must use the following OEM stock components in unmodified form: intake manifold, camshaft(s), cylinder head(s), rods, crankshaft.
16-1.3 Vehicles using factory OEM forced air induction may change or modify the following: air filter, intake plumbing, MAF/MAP sensors, throttle body(s), down pipes, exhaust manifold, exhaust system, boost control system.
16-1.4 OEM turbo charged vehicles are restricted to a 48.5mm compressor wheel inducer/minor diameter if a single non-OEM turbocharger is used. If non-OEM twin sequential turbochargers are used the larger turbo is restricted to a 48.5mm compressor wheel inducer/minor diameter. If twin parallel turbochargers are used, the inducer/minor diameter of the compressor wheels is restricted to 37.5mm.
16-1.5 Aftermarket intercoolers are permitted. The intercooler must fit fully within the bodywork.
16-1.6 Aftermarket or non OEM forced induction is not permitted on factory naturally aspirated vehicles.
16-1.7 Vehicles using naturally aspirated engines must use the following OEM stock components in unmodified form: rods, crankshafts.
16-1.8 Vehicles using naturally aspirated engines may change or modify the following: camshaft(s), valves, cylinder head(s), intake plumbing, air filter, MAF/MAP sensors, throttle body(s), exhaust manifold/header exhaust system.
16-1.9 The OEM block must be utilized. Engine may be rebuilt using OEM parts with a maximum .050” over bore. Pistons matching OEM specifications may be used.
16-1.10 Non OEM oil pans are permitted.
16-1.11 Accusump systems are permitted.
16-1.12 Vehicles must use a functioning catalytic converter within 18” of the OEM catalytic converter location. All exhaust flow must be through the catalytic converter(s) with the exception of the discharge from external wastegates.
The size of the catalytic converter(s) and the design is not restricted. The catalytic converter(s) must function. All exhaust components must be completely within the bodywork of the vehicle. Exhaust “tips” may extend no more than 3” beyond the rear bodywork.
16-1.13 Exhaust must exit behind the front axle, beneath, behind or to the side of the vehicle.
16-1.14 Transmission internal components may be replaced with OEM or aftermarket components. The gear ratios may not be changed and the type of gear and engagement must remain as OE designed.
16-1.15 Final drive gear ratio and differential type is unrestricted.
16-1.16 Non OEM alcohol or water injection systems are not permitted.
16-1.17 The OEM ECU must be used. The OEM ECU may be reprogrammed and/or a
"piggyback" ECU may be added.
16-1.18 Unleaded fuel must be utilized.
16-1.19 E85 fuel and Leaded fuel is strictly prohibited.
16-1.20 Radiator may be replaced with an alternate radiator mounted in the OE location.
Disclaimer: this section of the rules was taken from the official RLTA PDF file.
I have here posted the rules that stipulate what engine modifications are legal for this specific class.
I hope this thread can eventually act as a database for anyone interested in pursuing a "time attack" related build.
This is not and will not serve as my build thread, just hoping to get some discussion going. I'll most likely make a separate build thread.
----------------------------------------
16 ENTHUSIAST CLASS
The Enthusiast Class is designed to give street driven “grass roots” vehicle owners the ability to compete with basic bolt on modifications.
16-1 Engine and Drive Train
16-1.1 Engine must be OEM for particular make and model. No Engine swaps. Engine replacement is allowed ONLY from OEM engine from original make and model. Japan/European engine replacement is allowed as OEM factory trim. Drive wheel configuration changes are not permitted.
16-1.2 Vehicles using factory OEM forced induction must use the following OEM stock components in unmodified form: intake manifold, camshaft(s), cylinder head(s), rods, crankshaft.
16-1.3 Vehicles using factory OEM forced air induction may change or modify the following: air filter, intake plumbing, MAF/MAP sensors, throttle body(s), down pipes, exhaust manifold, exhaust system, boost control system.
16-1.4 OEM turbo charged vehicles are restricted to a 48.5mm compressor wheel inducer/minor diameter if a single non-OEM turbocharger is used. If non-OEM twin sequential turbochargers are used the larger turbo is restricted to a 48.5mm compressor wheel inducer/minor diameter. If twin parallel turbochargers are used, the inducer/minor diameter of the compressor wheels is restricted to 37.5mm.
16-1.5 Aftermarket intercoolers are permitted. The intercooler must fit fully within the bodywork.
16-1.6 Aftermarket or non OEM forced induction is not permitted on factory naturally aspirated vehicles.
16-1.7 Vehicles using naturally aspirated engines must use the following OEM stock components in unmodified form: rods, crankshafts.
16-1.8 Vehicles using naturally aspirated engines may change or modify the following: camshaft(s), valves, cylinder head(s), intake plumbing, air filter, MAF/MAP sensors, throttle body(s), exhaust manifold/header exhaust system.
16-1.9 The OEM block must be utilized. Engine may be rebuilt using OEM parts with a maximum .050” over bore. Pistons matching OEM specifications may be used.
16-1.10 Non OEM oil pans are permitted.
16-1.11 Accusump systems are permitted.
16-1.12 Vehicles must use a functioning catalytic converter within 18” of the OEM catalytic converter location. All exhaust flow must be through the catalytic converter(s) with the exception of the discharge from external wastegates.
The size of the catalytic converter(s) and the design is not restricted. The catalytic converter(s) must function. All exhaust components must be completely within the bodywork of the vehicle. Exhaust “tips” may extend no more than 3” beyond the rear bodywork.
16-1.13 Exhaust must exit behind the front axle, beneath, behind or to the side of the vehicle.
16-1.14 Transmission internal components may be replaced with OEM or aftermarket components. The gear ratios may not be changed and the type of gear and engagement must remain as OE designed.
16-1.15 Final drive gear ratio and differential type is unrestricted.
16-1.16 Non OEM alcohol or water injection systems are not permitted.
16-1.17 The OEM ECU must be used. The OEM ECU may be reprogrammed and/or a
"piggyback" ECU may be added.
16-1.18 Unleaded fuel must be utilized.
16-1.19 E85 fuel and Leaded fuel is strictly prohibited.
16-1.20 Radiator may be replaced with an alternate radiator mounted in the OE location.
Disclaimer: this section of the rules was taken from the official RLTA PDF file.
04-06-14, 02:43 PM
#2
Rotary Shack
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So far I'm thinking the following;
Stock turbo or maybe BNR Stage 1 and SAFC or Rtek for tuning, hoping for 240-260 at the wheels.
Since I'm on a budget ($1000), I'm thinking about staying with the TMIC, as I've read I can probably safely run low to moderate boost levels without having too much a detrimental effect on the IAT.
https://www.rx7club.com/2nd-generati...cooler-920506/ discussion thread.
Also unfortunately because I'm in CA, I'm limited to 91 octane and also because of the class rules, I cannot use alcohol or water injection.
Stock turbo or maybe BNR Stage 1 and SAFC or Rtek for tuning, hoping for 240-260 at the wheels.
Since I'm on a budget ($1000), I'm thinking about staying with the TMIC, as I've read I can probably safely run low to moderate boost levels without having too much a detrimental effect on the IAT.
https://www.rx7club.com/2nd-generati...cooler-920506/ discussion thread.
Also unfortunately because I'm in CA, I'm limited to 91 octane and also because of the class rules, I cannot use alcohol or water injection.
04-06-14, 05:02 PM
#3
Rotary Shack
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I've been reading up on the Rtek and I think that's the direction I'll be going.
Threads:
https://www.rx7club.com/2nd-generati...-mods-1057772/
https://www.rx7club.com/rtek-forum-1...ethods-827389/
Threads:
https://www.rx7club.com/2nd-generati...-mods-1057772/
https://www.rx7club.com/rtek-forum-1...ethods-827389/
04-06-14, 05:38 PM
#4
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hmm i think the turbo will limit your power to something around 250whp, which you could do on a stock ecu, although since its going to see WOT for long periods, you should probably run a bigger fuel pump and at least bigger secondaries. Rtek would be a good idea.
the BNR stage 1, uses a V trim wheel, which is actually larger than 48.5mm, so its not legal, the biggest T4 wheel i see is the super S. i'm sure Brian could build a super S stage 1. i looked at the S before, and it flows about 10% more air than the stock wheel.
the twin turbo option is only a pair of T25's, so i'm not sure that's really enough better.
for an IC you should do the intercooler and a half thing the japanese do, £Ð£Á£Ò£Ô£Ó¡¡£Ì£É£Ó£Ô you get a better IC, but its not blocking the radiator.
the BNR stage 1, uses a V trim wheel, which is actually larger than 48.5mm, so its not legal, the biggest T4 wheel i see is the super S. i'm sure Brian could build a super S stage 1. i looked at the S before, and it flows about 10% more air than the stock wheel.
the twin turbo option is only a pair of T25's, so i'm not sure that's really enough better.
for an IC you should do the intercooler and a half thing the japanese do, £Ð£Á£Ò£Ô£Ó¡¡£Ì£É£Ó£Ô you get a better IC, but its not blocking the radiator.
04-06-14, 11:07 PM
#5
Hey, I work at a place where we also do time attack in LA county, specifically, buttonwillow GTA annual time attack. We've been participating since 2010 successfully! Have fun, but from what I know, competition is pretty tough. Guys are getting faster every year, it's amazing. Guys in street class are going to be around 1:55 street class at button willow configuration 13. I know the guy that won enthusiasts last year, I forgot the time.
No camshafts in the cyl engine restriction sounds like no porting if you bring a rotary. Go for fun, a lot of shops will be out there to claim bragging rights
No camshafts in the cyl engine restriction sounds like no porting if you bring a rotary. Go for fun, a lot of shops will be out there to claim bragging rights
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