GSMnow
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- 165
- Location
- Santa Clarita, CA USA
Maybe someone with an LS400 can answer these for me.
The engine in question is most likely going to be a 1993. At what RPM does the stock ECU shut down the engine? Is it a brick wall cut out, or a smooth loss of torque? If you have the shifter in manual second, how many MPH is it going when it cuts out? (to figure torque convertor slippage). In manual second, will it still downshift to first when you get on the throttle hard at low speeds, or does it stay in second? Is there any form of rev limit altering device available like the HKS FCD or such to raise or eliminate the rev limiter?
The rest of this post is explaining my reason to rev
I have not received my engine/trans/ECU yet, but I have been doing some ratio calculating and I am hoping I can rev this thing a bit higher than 6000 rpm on the stock ECU. I know the power falls off up there (especially with stock cams and all) but I have a specific reason. My rear end is a 3.727 and I autocross race on tires only 22.6 inches tall. With the stock A341E trans from the LS-400 this puts me under 70 mph at 6000 rpm in second gear even without figuring in torque convertor slip. With my turboed 22RE I was revving it out to 7200 rpm with a W58 trans to make most courses without needing that extra shift to 3rd. That motor was cammed for a power peak under 6000 and my best 0-60 mph runs where from shifting at 6200 or so, but NOT shifting to 3rd on a tight autocross course was much faster considering I would be dropping back to 2nd in a heartbeat since the courses have about 40 turns in 40 seconds. The last season with the turbo motor I only used 3rd at a huge nationals event where I topped out over 80 mph so the shift was not a big deal. On most course run locally, I was able to lock it in second and run all day with maybe a tap of my rev limiter at the very fastest portion of the course. Even running the auto trans, I hate to have it shifting because it upsets the balance of the car while cornering beyond normal limits. The engine braking of staying in second makes the car rotate very nicely in drop throttle. 3rd won't pull down like that, and the down shift could come mid corner. OUCH. I really would like a manual trans and a settable rev limiter, but as I am building this as a California legal car, I must run the stock ECU and for now that may require the stock auto trans to be there as well since I must run the US spec ECU. The car must test as if it is a stock LS-400. Any mods have to be CARB emissions approved.
Gary M.
The engine in question is most likely going to be a 1993. At what RPM does the stock ECU shut down the engine? Is it a brick wall cut out, or a smooth loss of torque? If you have the shifter in manual second, how many MPH is it going when it cuts out? (to figure torque convertor slippage). In manual second, will it still downshift to first when you get on the throttle hard at low speeds, or does it stay in second? Is there any form of rev limit altering device available like the HKS FCD or such to raise or eliminate the rev limiter?
The rest of this post is explaining my reason to rev
I have not received my engine/trans/ECU yet, but I have been doing some ratio calculating and I am hoping I can rev this thing a bit higher than 6000 rpm on the stock ECU. I know the power falls off up there (especially with stock cams and all) but I have a specific reason. My rear end is a 3.727 and I autocross race on tires only 22.6 inches tall. With the stock A341E trans from the LS-400 this puts me under 70 mph at 6000 rpm in second gear even without figuring in torque convertor slip. With my turboed 22RE I was revving it out to 7200 rpm with a W58 trans to make most courses without needing that extra shift to 3rd. That motor was cammed for a power peak under 6000 and my best 0-60 mph runs where from shifting at 6200 or so, but NOT shifting to 3rd on a tight autocross course was much faster considering I would be dropping back to 2nd in a heartbeat since the courses have about 40 turns in 40 seconds. The last season with the turbo motor I only used 3rd at a huge nationals event where I topped out over 80 mph so the shift was not a big deal. On most course run locally, I was able to lock it in second and run all day with maybe a tap of my rev limiter at the very fastest portion of the course. Even running the auto trans, I hate to have it shifting because it upsets the balance of the car while cornering beyond normal limits. The engine braking of staying in second makes the car rotate very nicely in drop throttle. 3rd won't pull down like that, and the down shift could come mid corner. OUCH. I really would like a manual trans and a settable rev limiter, but as I am building this as a California legal car, I must run the stock ECU and for now that may require the stock auto trans to be there as well since I must run the US spec ECU. The car must test as if it is a stock LS-400. Any mods have to be CARB emissions approved.
Gary M.
