the reason i wrote that is because i have totally changed my oppinion of big turbos/converters on stock trucks.
yes, you need more converter to spool a bigger turbo.
yes, a big converter sucks on a stock motor.
since my truck has been thru many combinations now, ive realized a much better way to get a bigger turbo to spool up, is to have a well matched parts combination with dead on the money tuning. i can easily get 20psi from my PT52 at just over 2000 RPM. a PT52 is a small turbo for my combination, but the fact is, small turbos are funner on the street.
if you wanna go fast for cheap, sure slap on a bigger turbo and a converter and you will go faster, but at the expense of drivability. there are a bunch of people here that will disagree with me, but this is my oppinion, and im sticking to it!
a stock motor is typically driven well below the stall point of a 9/11 converter making much of the usable RPM range mushy and not fun to drive at low speed. people will argue that we have TC lockup, but that only happens when your speed is already up (third gear), so we will ignore that for now. since it only applys to highway/ country roads.
example: your cam/engine makes power in the 0-4500 RPM range and you just installed a 9/11 converter that was susposed to stall around 2800, but actually stalls around 3200 when the turbo spools up, because we drive torque monster trucks. not very much fun
another example: you have a cam/engine that makes power in the 1500-5500 RPM range, and you have the same big turbo with the same converter. drivability is wonderful, because you have a motor that makes power in a range of rpm that is matched to the converter. more fun
there is also another consideration that i havnt mentioned yet. "transmission shift points" my waller built tranny has a much higher line pressure, and part throttle shifts as well as full throttle shifts have been pushed upwards, even though im using a stock govnor. part throttle shifts usually occur around 2500RPM. it was built like this to handle the power a bigger turbo makes, and these are the side affects. that doesnt mean they are bad. actually with my cam/motor combination, the higher part throlle shifts are great, because once again they better match the RPM range of the cam and also the 9/11 converter.
up until this point, everyone has been using a 412 (or smaller) cam because the lower duration, was easier to chip tune for. in my oppinion, you should choose a cam based on the effective RPM range that matches the rest of your combination, not how easy it is to chip tune. hopefully with all the new motor combinations coming out we will see readily available chip calibrations that work with the larger cams and larger injectors. i still cant say enough about how streetable the 512 cam is. a lot of people probably think its a shaking spitting monster cam, with poor drivability, but thats not the case at all. it has almost no lope at idle, and is MUCH more fun to drive when you have a turbo that requires a converter.
BTW there are calibrations for the stokes grind cam out right now. and im currently working on one for the mccoy 512 cam.
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