is it bad if i boost prep the engine but don't add turbo or anything to create boost? basically im wondering if i can boost prep it now during the rebuild and then drive it stock until i decide whether or not to go turbo.

 

Now what do you mean by Boost prep.... As in Low compression rotors? (If your 12a, pretty sure you cant go low compression rotors....) but yah, you can do whatever you want and still drive it. There are even people that have removed the turbo from their engines and still drive no problem.

 

well that is basically what im getting at. just wanted to know if running a boost prepped engine without a turbo was bad for the engine. thanks for the help.

 

well we need to know what you mean by boost prep, some things can make a difference.
for instance, if you go with low comp. rotors (13b only) you will have less power NA and it won't be as crisp.
also, i've heard boost prepped carbs run pretty rich NA (if you go blowthrough).
i can't really think of anything that would prevent driving it though.
share your ideas, we like to hear about em.

 

this will not be an issue. usually building a motor for boost means making it stronger... how could this be bad???? you CAN get low compression rotors for the 12a, just alot harder to find. but either way, 13b/ 12a/ whatever... without the turbo it will just be slow that's all. if you rock out a boost prepped carb, it will be fine, just jet it for the application at the time.

 

fbII
for my own knowledge, i remember robert saying something about a boost prepped carb being... laggy? (can't think of a better term) no matter what the jetting (if you run it NA)
i can't find the thing he said that made me think of this.
do you have any insight?

 

it depends on what carb. if it's mexico (robert) then he was probably referring to a sidedraft as that is his carb of choice. WHAT UP CHEEEEEEEEEEEESE!!!!?!?!?!?!?!!!!

when you have the turbo setup on and in effect, then the lagginess could arise from the heavy jetting mix. on a nikki it wouldn't really be any different, because the actual "boost prepping" of it doesn't touch the jetting. altho, there is no choke, vaccum secs, etc... so it really depends on your driving style.

i drive mine everyday and can cruise around and even drive semi-spirited off boost and it responds flawlessly. altho..... i've put alot of time in to tuning this carb. with it setup as it is, if i took the turbo off and didn't touch the carb it would be a dog at full throttle from the fat mix up top and closed air bleeds. ahahaha

it's all in the jetting on a nikki... i can't account for a side draft tho. give him a ring, he'll set you straight.

 

Can't you effectively (although not accurately) lower the compression on any rotor by machining material off of the rotor face?

 

yes, that is one way of doing it.

 

i don't know if i'd bother though.
many people have done fine with the 12a's 9.4 ratio, if you want it lower go with s5 TII rotors which have 9.0 or s4 which is 8.5.
for 99% of us i don't see i reason to go any lower.

 

im new to the whole boost/turbo thing so please bear with me. yes i am referring to building the n/a 12a for lower compression and just not adding a turbo to it. more specifically would it be possible to build iit for low compression as far as seals and gaskets go but keep all of the internals stock until i have the time/money? it is basically a question of prep for the future.

 

i wouldn't worry about lowering the compression.
just do lots of research and when you do run it make sure nothing goes out of whack.
as far as engine internals, that's the great thing about a rotary, there really isn't too much to improve upon.
just use quality parts and make sure all your housings are in spec.
if you aren't cranking high rpm's there isnt much to worry about.

 

you are still thinking piston engines... where you can just change the head gasket and raise/lower compression in a sense. on a rotary... nope. rotors decide all that.

like the danish said, there really is no reason to drop down if you are building your 12a. just build the engine right and TUNE TUNE TUUUUUUUUUUNE. you'll be fine and make plenty of power to put a smile on your mug.