ks71z28

My new motor is a 389, 10.5:1, 238/240 .558, 112 hyd roller, Afr 195 comp heads, HSR intake. Old motor made 458 hp, new motor should be well over 500 hp.

My question is will a larger than 58mm throttle body help with the additional HP? ASM makes a monoblade TB, any experiece with that? Car is autocross machine, so throttle response is key, I know large area TB's can be a pain to tune.

Also I am doing a carbon fiber intake plenum, prototypes are almost completed ready to test, check out my site

www.customworksproducts.com

brutalform

Keep your 58. It will be fine. Big bucks for a mono blade.

Orr89RocZ

iTrader: (20)

Yep, 58 will do. I had about 500hp on my 383, maybe more. 58 worked great and throttle response was also good. I think the large plenum of the HSR helps abit with overall throttle response.

ks71z28

that is good to know. I also have a larger volume plenum I am producing out of carbon fiber, which should help out the top end, as well as keep intake temps lower

GTA Sammy

iTrader: (1)

Carbon Fiber Plenum looks awsome!!!!
There are a ton of guys with HSR's out there!!!

1 DwnCam

At what power level are the monoblades used?

Orr89RocZ

iTrader: (20)

There are some guys using them to make sure the motor is seeing 100KPA instead of 95-99 kpa. There is always a slight restriction and you may not see perfect atmosheric pressure at WOT. Monoblade can be used to make sure you have no restrictions but really wouldnt be beneficial in flow until probably 600 hp. I believe the general rule of thumb is 2.2 cfm per hp and a monoblade can flow around 1300 cfm.

ks71z28

At 2.2 CFM my motor should need 1100+ CFM looks likely that I will be at the absolute edge. I do have a 4" intake tube all the way to a very large cone filter ahead of the core support, so the biggest restriction will be the TB. I wish they were cheaper, so I could test one on the dyno. I am a bit leary about the supper large opening, which can create part throttle issues when tuning. I autocross the car, so top end HP isn't the biggest issue, mid rang tourque is paramount, and the car already made almost too much low end power.

Orr89RocZ

iTrader: (20)

Monoblade is big money. I dont think its necessary. Your combination is pretty stout, and the 58 should feed it.

My car still made 400whp thru the stock TPI style intake/MAF. I switched to a 3.5" CAI setup and didnt pick up anything at the track that I could notice.

Tony89GTA

iTrader: (7)

That's a pretty cool intake piece your building, is there a chance this will fit under a Trans Am hood, also what's your projected cost for this sucker?

joeblue83

iTrader: (8)

I run a 52mm throttle body, and am making 476hp.

articwhiteZ

iTrader: (56)

58mm is fine.

RedGut86

ks71z28

I have no idea if it will fit under a 3rd gen hood as is. It is no taller than the stock piece, but it is about 1 1/2" wider on each side. There is a possibility that it can be made to be shorter in height by about 1/4", but that is easier achieved by milling the base manifold. Price is likely to be about $1000, as this is part takes a great deal of time and materials to produce. When finished the thickness of the layed up part is nearly 1/4" thick, I tell you you could park your truck on top of this thing!

1989GTATransAm

iTrader: (3)

"I am a bit leary about the supper large opening, which can create part throttle issues when tuning"

Not an issue at all. I'm running monoblade. By the way I notice some of the LSX guys are now running 100/104mm MAFS, throttle bodies, lids and they are finding more power. Near as I can tell that is about equivalent to a monoblade.

Ronny

iTrader: (1)

Is there not a racing class for circle track or whatever that requires a 2 barrel carb. I believe they are small blocks with a lot of HP. How can they get 400 HP with a 2 barrel?
I currently run a 7.4L GM TBI. Rated 670 but with injector tower in the way may only be 640 or so? I suspect my motor is 350 HP 350 CID(w/o N20) and I am key on 98MAP and logs show 94-95 MAP. I just began install of N20 so the small TB should not be an issue there. Not yet 100% installed however.

Orr89RocZ

iTrader: (20)

If you can get that to fit under a C4 vette hood, you will have a good market for selling those plenums. Alittle pricey tho, but its understandable for the material. C4 guys would love an intake that would fit under stock hoods.