Extruded Hone Plenum + 70MM TB's

[ASASN]

Extruded Hone Plenum + 70MM TB\'s

Hello All!!

I was wondering if doing the plenum and adding 70MM were really worth it with the stock 488ci!
Even say on a head and cam package....

Is there a benefit to doing this.....is the cost worth the gains??


Thanks for the help.....


Mike P.

BTW.....CAN ANYONE TELL ME WERE I CAN FIND A SET OF 3.31/3.33 GEARS????

 

[joe117]

Re: Extruded Hone Plenum + 70MM TB\'s

If you were going to race on an oval track where you never used the lower half of the rpm range, it might get you some more power.
I'd say it wouldn't buy you enough top end to make up for what it would cost you at the lower end.

Cost wise? I don't know. I just don't think you want to do it.

 

[George Bryce]

Re: Extruded Hone Plenum + 70MM TB\'s

C-5 guy, I got some 331s, nananananannaannanan! I still want them....2bad. I read somewhere that that strud hone stuff will come loose in yo motor and burn up yo cylibles.
Go ahead and get your 70 milomeba tbs...cause you go soup up yo motor sooner or later...I know you will. GB3

 

[newredrt10]

Re: Extruded Hone Plenum + 70MM TB\'s

Joe 117 is right, I found out the hard way.

3000 rpm 239.5 rwhp 419.3 rwtq
3500 rpm 305.2 rwhp 457.9 rwtq
4000 rpm 361.9 rwhp 475.2 rwtq
5200 rpm 437.0 rwhp 449.8 rwtq

The car also had 7:1 rockers and headers. The car would of been a dog if it did not have 3,73 rear to use the higher rpm range. Save your money put in a cam and heads or maybe a s/c or a TT

 

[George Bryce]

Re: Extruded Hone Plenum + 70MM TB\'s

AASASAN, put the Pro Shot fogger on it!!!!!!!! That otta do it! GB3

 

[FE 065]

Re: Extruded Hone Plenum + 70MM TB\'s

The intake runners going to each cylinder head port are already very smooth.

There just isn't much to abrade away with the extrude clay ****.

Which leaves the just the entrance way to each runner to massage.

$900 some dollars and about 9hp are the cost to benefit facts as I recall.

 

[ASASN]

Re: Extruded Hone Plenum + 70MM TB\'s

Hey guys thanks for the help!!

Hey GB3, what's up my friend.....I'LL GET MY 3.33 ONE WAY OR ANOTHER!! You better not leave them laying around the shop, I may come visit when your gone....nanananan!!

I'm going to do a head & cam swap next week, so I guess I'll leave the plenum alone!
I guess I should just add TB's, port match them to the plenum(?), and port match the plenum to the heads......and be good to go?!!

Thanks for the help!! Anything other suggestions??

 

[joe117]

Re: Extruded Hone Plenum + 70MM TB\'s

I'd wouldn't get rid of the stock tbs at first. You should dyno with stock and 70mm.
Everything I said about hone and 70mm tbs is also true about 70mm tbs without the hone. They may be just too big.