need some help with the cam selection

[turbogreg]

my goal is to have a consistent high 10 second car, so it's time to open up for the heads, ported intake, and cam. i'm searching for a set of ported irons right now. first question is do i really need the bigger valves or not? also what cam should i go with. flat tap or roller setup? the roller setup looks a bit more pricey but is it worth the extra power? if so which cam would be a nice choice for my setup? the car is an 87 GN t top car. GT6152E, RJC FMIC, 3'' dp, 2.5'' hooker catback, 60lber's, alky kit, dynotech hi-po trans with 10.5'' 3200-3400 l/u, eaton posi, and all the other good stuff. unopened 53k original mile motor. don't want to go too crazy really and want to keep the bottom end in one piece. figured heads and cam i can keep the boost around 23 psi and reach my goal much easier than cranking up the boost to 27 ish and possibly detonating and popping a head gasket.

thanks in advance,

Greg

 

[84TXGN]

For a consistant 10 sec car I would go with bigger valves. For the cam I would certainly go roller. Its pricey but you don't have to worry about wiping a lobe. I cannot say which cam would be best for your car as I don't run a roller(yet) but cam choices do not seem to be quite as important when it comes to these motors. These cars seem to perform well into the 10s with mild cam upgrades.

 

[Lynn D. Brown]

Cams

I have wiped lobes with a roller cam. U still have to watch and not get too much spring pressure

 

[yullose]

I'd focus more on a complete combination, rather than a camshaft.

There are guys running roller cams and 70-series turbos that still can't get out of the 11's.

What you have now can push you into the 10's.

 

[turbogreg]

getting a set of ported irons with big valves. now i gotta decide on the cam. the heads are setup for a roller cam all ready to go. now i just gotta decide what cam to go with. had the car out yesterday, was running good at 26-28 psi with no knock at all. gotta love alky. :biggrin: was fun until i decided to play with my buddies vette (720whp/670trq). from a 40 roll he couldnt hook and i ran away, from a 60 roll he peddled it and finally hooked and ran away bad. scary car with stupid top end that thing.


Greg

 

[TURBOELKY]

getting a set of ported irons with big valves. now i gotta decide on the cam. the heads are setup for a roller cam all ready to go. now i just gotta decide what cam to go with. had the car out yesterday, was running good at 26-28 psi with no knock at all. gotta love alky. :biggrin: was fun until i decided to play with my buddies vette (720whp/670trq). from a 40 roll he couldnt hook and i ran away, from a 60 roll he peddled it and finally hooked and ran away bad. scary car with stupid top end that thing.


Greg

MAN, your pushing it with 28 psi, alky or not! I agree up there with Lynn, you can whipe a lobe with a roller too. Rollers are good for something around 6%-8% max over flat tappet. For what your trying to do, I would stick with flat tappet, spend the extra 600 bucks on something else like your heads. If you whipe a lobe on a flat tappet, its not because it was a flat tappet, its because of break in error, or improper spring pressure's. Good luck on your decision. p.s., I've never whiped a lobe in any of my v8's nor my 6 banger, I always run an isky cam/spring set up.

 

[Alky V6]

A 212/212 will do fine.

 

[gnxtc2]

Greg

If you with bigger valves, the cylinder will block the intake valve. You then have to "eye brow" it. Just take a look at a stock HG, you will see that it is not a perfect circle.

Don't go more than 214/214 on the cam.

At this point, I would pull the motor and beef up the bottom end. You will have the intake, exhaust manifold, accessories, heads, front cover off. Another hour, the block will be out. You won't be bent over fighting under the hood.

If you need a hoist, I have one that you can borrow. I can pull a GN motor in 2-3hrs.

Billy T.
gnxtc2@aol.com

 

[turbogreg]

was thinking of going with a 212/212 roller cam from fullthrottlespeed. i know 28 psi was pushing it cranked it back down to 22 psi today. i'm not gonna open the motor til after my birthday(end of may) but trying to get everything i need together so i can bang it out in a weekend instead of having the car down for like a month or two. if i keep the boost down should i still be worrying about the bottom end? only thing that scares me about pulling the motor is the $ for machining. all i'd need would be a set of pistons and main caps for what i'm looking for no? how pricey can that turn into being? another reason i want to go roller is that i plan on building the bottom end next year and i don't really want to have to switch setups, would rather do it once and be done. billy will give ya a ring later today, thanks for the suggestions everyone.


Greg

 

[Ttype6]

I know 28 psi was pushing it. If i keep the boost down,should I still be worrying about the bottom end?

28 psi. on a stock,unopend motor,with alky isn't as crazy as it sounds. It's important to understand that the pressure your boost guage is measuring is the pressure in the intake manifold. The cylinder pressure is a whole other issue. The stock unported heads,unported intake,and low lift and duration cam,create a fair amount of restriction between the intake manifold and combustion chamber. Because of this restriction,your cylinder pressure isn't as high as it might be.When you get rid of this restriction by installing a bigger cam,better flowing valves,larger better flowing ports in the heads,and larger better flowing ports in the intake,your cylinder pressures will rise significantly.With these parts added,it will be much harder to safely make big boost,as your motor will be less tolerant of too much boost and/or timing. It will be much more important for your tune to be right on.This means that the answer to your secound question is yes. At any given boost amount your motor will be making more torque and horsepower. With this new combination,your motor will probably make more power at 22psi. than it did before at 28.

 

[turbogreg]

that's exactly what i want. more power at much less boost. thinking about ordering up that new powerlogger from fullthrottle next week to help tune. anyone using it yet? i mean not too too much to tune really is there? just tune for no knock and can add boost little by little. if i can make more power at low 20's psi then when im at 26+ right now that would be great. gotta love alky tho, hands down best mod i've done to the car. hell even let the gf take the car out the other day at low boost(21-22ish) and she handled it well.(she's got a bolt on 99 z28) with the heads cam and ported intake i think that same 22 psi will be a bit different tho :biggrin:
thanks for the info Ttype6 and everyone else. this boards much more helpful than the others, that's for sure. i think the stock bottom end should be ok with a safe tune tho, will find out. how much would i be looking to spend labor wise if i decided to do the main caps and the pistons?

Greg

 

[Ttype6]

just tune for no knock and can add boost little by little. Gotta love alky though, hands down best mod i've done to the car. iIthink the stock bottom end should be ok with a safe tune though, will find out.

Yes,no knock is everything. It's hard to beat a knock sensor,Hood mounted fuel pressure guage, and boost guage as tuning tools. I use the Scanmaster as a knock guage. I love my Alky Control kit. Your right,it's one of the best purchases for these cars. The stock bottom end can handle an amasing amount of power. I chose to girdle mine for extra insurance. Hot rodding is a drug,that you build a tollerance too. You need more and more of the drug to get a good buzz. The first thing you want to do after you add 100 hp. is too add 100 more. As soon as you do the heads,intake,cam,pistons and bottom end,you'll soon figure out that you're only a turbo and injectors away from much bigger power. Make the bottom end as strong as possible now so that in the future more power is a simple bolt on process. There's now way that billet caps can be as strong as a girdle. As far as how expensive the machining is,who cares? No one cares how much the drug costs,only that it can be obtained. Man oh man, hot rodding is so stupid,wasteful,and selfish. On that note,I think it's time for me to throw $1,000.00 into my rear end. I didn't mean that the way it might have sounded. Happy Hot Rodding!

 

[ttypewhite]

I can sell ya a 212/212 flat tappet for cheap if your interested. With Champion ported irons and this cam I went 10.30@131mph. Pm me if your interested.

 

[49-blues]

TTYPEWHITE- you have some nice cars! what size firestones do you have on the front of the white car and who did the body work? They look great!

 

[ttypewhite]

TTYPEWHITE- you have some nice cars! what size firestones do you have on the front of the white car and who did the body work? They look great!

Thank you Sir, the Firestones are 26" and the body work is done at my buddies shop, RustyAuto.

 

[turbogreg]

thanks for the offer ttype but i think i want to go roller. the springs are all setup up for a roller setup anyway. always see your sig with the white T, looks great. nice numbers too! how streetable is that setup you are running? 130+mph traps are always fun, what turbo is that with?
as for the bottom end i really dont want to build it up too much yet. i'm sure once im done with school(junior in college) i'll have more time and money to spend and be able to build a block the way i want it. ha, i know how many goes into these. i'm just happy i sold the stealthTT i had and got the GN. so much easier to mod. i try not to complain about how much the parts are for our cars because my buddies cars are MUCH more expensive to mod. i'll try and get a clip of my buddies 02 zo6. just got it back(383 stroker w/t76 turbo), just made 720rwhp/670trq at 13.5 psi. talk about some top end, but i got him covered from anything under a 50 roll. ha traction always helps i believe i have his dyno video , i'll try and post it later today, crappy quality video though. ha ttype6, i think i'm gonna need a grand into my rear end too. i decided to come down the GF's driveway this morning(very steep and couple hundred feet long, out in the sticks of CT) with a set of her slippers because my shoes were MIA. BAD IDEA. u gain alot of moment in slippers and ice and took a header 3/4 of the way down. oddly enough her neighbor has an 86 GN, but keeps this thing outside in his driveway all the time! it's covered in snow and ice as we speak.

 

[ttypewhite]

thanks for the offer ttype but i think i want to go roller. the springs are all setup up for a roller setup anyway. always see your sig with the white T, looks great. nice numbers too! how streetable is that setup you are running? 130+mph traps are always fun, what turbo is that with?

Its 110% street car. As long as its sunny and dry, I am in it. the times were done using a 71GTQ turbo.

 

[turbogreg]

guys, gonna order up the 212/212 hydraulic roller cam from fullthrottlespeed this month. heads should be here next week and have a few more bucks to play with coming april so debating about doing the bottom end. am going to stick with the 61mm since 10s is all i want for now. 10.9x's would make me a very happy camper in street trim(drag radials,pump/alky) so maybe i shouldnt bother building the bottom end. had a few runs today at low boost(21-22psi) with my buddies turbo zo6(720rwhp/670rwtrq) and my other friends evo(358awhp/370awtrq). vette runs were good until he hooked then well...you know the rest. and the evo and i were glued together 40-110+ the whole time with me with a passenger and still on low boost. at my usual 26-28psi i think it would have been a whole different ball game plus i hate going from highway rolls, our bricks aren't exactly mean't for em. what kind of numbers could i realistically expect to put down with the ported irons, 212/212 roller, ported intake, 61mm turbo, rjc fmic, and all the rest of the bolt ons.

Thanks,

Greg

 

[Blazer406]

All those parts are going to pick you up.... but you may want to step up the hair drier before it is over. I think the 6152 is a great turbo.... but I don't think it is a consistant 10 sec turbo on a full weight car like you want. Something along the lines of a GT6776 dual ball bearing ought to get it done with the same converter IMHO. Obviously, the fuel system and all the other complementing parts will need to be there for a "total combination". It's the combination that lets guys go occasional 10's on a TE44.... or mid 11's with a 70 turbo... it can make or break your ET for a given size turbo.

 

[turbogreg]

lightening up the car a bit with some fiberglass goodies. i was debating about the gt6776bb but if i ever go bigger it's gonna be a 70mmbb and i don't really wanna drop that 2 grand on a turbo just yet. i'm pretty sure my bottom end wouldnt be happy with that kind of turbo either. i'll post the times and numbers later in the spring with the setup. hopefully can get everything bolted up by end of april so we shall see. i think consistent high 10s should be very reasonable with the 61mm with the heads and cam. how fast has the 6152e gone anyway? everyone i see running them are usually on the stock unopened block so has this thing even been pushed that much?

Greg