MSM69Z28

just joined. although, i am not a first gen, i see the power adder forum very useful. not many other forums with much experience with the roots blowers, specifically the 144.

here's my combo. please make recommendations.

1 piece seal 350 bored .030 over
4 bolt billet splayed caps
4340 eagle 3.75 crank
4340 eagle H beam 6.0 rods
custom wiseco pistons (8:5:1)
64 cc 23 degree trick flow heads
fluidampr balancer
arp studs on all motor
solid roller cam and lifters (crower) specs:
286/296 252/259@.050 with .608/.625 114LSA
1.6 full fulcrum RR
(haven't got the carb yet but either 950cfm or 1050 cfm 4150)
B&M 144

all is purchased already except carb.

question: boost with pulley combinations max engine rpm of 7k:

evaluating the 7" crank 10rib and 2.5" 10 rib blower pulley for max boost. will it be too hot? no benefit of added boost. how much?

or try opposite.. 6" 10 rib and 4.10 10 rib for lowest rpm and heat (closer to holley's recommended blower spinning rpm)?

should i consider chunking this 144 and go with the vortech blow through for the extra cash?

help. rebuild under way. decision need made soon.

thanks,

mike

paul_huryk

That's gonna be one hell of a high revving motor when you get done.

The 144 will rev too high and the heat produced will be rediculously high at the boost (and cfm) the motor will need.

You should (as you suggested) go for another blower type, someone will buy it from you for good $.

MSM69Z28

are you suggesting the 7"/2.5" combination is too much or the low ratio as well (6"/4.10").

with the 6"/4.10" pulley combination, i would only be at like 21000 blower rpm at 7k engine rpm where as the first combination would go over 40,000... probably too much to endure.

considering spinning it 21000 thats within the holley recommendations, but WILL IT MAKE ANY BOOST AT ALL. it won't e worth all the trouble for like 2-3 pounds.

who's got examples of pulley combinations with boost on the engine combination?

vortech kit will really set me back.. just want to make sure i can't make what i have work for me.

thanks,

mike

Z28ricer

iTrader: (2)

Remember the vortech will also not build the low end boost the roots does, you may want to look at some of the others available, maybe a whipple ?

Kingtal0n

Lets play a game... ready? True or false:

144 Blowers 220% overdriven will produce more than 4 PSI of boost on a 383 CiD Engine: False

144 Blowers like to spin more than 11,500 (5500~~ Engine) RPMS: False

144 Blowers require Forged Crank / Rods: False

144 Blowers eat your gas mileage up: False

144 Blowers work well with 286/296 252/259@.050 with .608/.625 114LSA Cam Specs: FALSE

144 Blowers require super low compression i.e. 8.5:1: FALSE

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As you can see, your working with a mismatched setup. your engine would make more power WITHOUT the blower.... In fact, your engine is more of a 671 Roots blower engine. 4-8%~ Underdriven with that cam will produce roughly 8-10 PSI of boost on your engine, and you have the forged parts for it. However, that duration is a little high for ANY roots blower... you will soon find that no roots blower is very friendly above 6,000 Rpms, and thats where that cam is headed. Then add the fact its a 114 LCA... forget it, cylinder pressure will skyrocket and you will blow a headgasket if you hit it below 2K Rpms... What Im trying to say is if your going with a roots blower, you need to re-think your cam selection, blower selection, valve train, etc... Since you purchased it all, already, I would Look into a 671 and get a better cam suited for that application. or go centrifugal... bite the bullet. Sure you can spin that thing up and make power, but say goodbye to a reasonable stall and a reasonable idle and reasonable gas mileage....

MSM69Z28

thanks for the feedback so far fellas.

Kingtalon, i believe you are accurate in much of your response. i value your advice especially considering you are running this same blower. i do notice that you are running quite a large cam as well. over 300 duration has got to end up similar to my same duration at .050". is that not working out for you?

if i understand correctly though, you don't think this blower would make even 4 psi on my 383 and that these blower's don't like above 11,000? man, i don't even think the slowest pulley setup can get down to 11,000 at 5500.. barely maybe...

damn, maybe the vortech is the way to go? just kills me to drop 2k more into this car right now. for 2k, this vortech had better make at least 100HP over the 144 set up to be anywhere near worth it? think possible?

i will say though that i don't think the engine n/a would make less than with the 144.. that might a slight exaggeration.

Kingtal0n

<b>over 300 duration has got to end up similar to my same duration at .050". is that not working out for you? </b>

Oh, it works fine, but my .050 - .050 Duration is only 234/244... Which is still alot more than I would normally use... HOWEVER, I plan on stepping up to a 671 after this engine is broke-in, so by using the 144 I am keeping engine stress low while I test and tune the engine for daily driving... eventually the cam will be replaced with a solid roller with less .050 - .050 duration and alot less advertised. I have swapped 3 cams into this engine so far, and this is the best one yet because of my restrictive heads, the extra duration helps alot... But when the heads get changed to some 220CC runners and 2.08 valves... Extra duration will only hurt my tiny blower... thus the 671... if feasible.

Right now the 144 puts out a little more than 4 PSI of boost on my engine, and its running 220% overdriven which is the fastest Holley recommends, and the smallest pulley combo you can get. ITs supposed to be good for 8-10 PSI on my engine, but as you can see the camshaft robs a good bit as does my street exhaust. The 220%over-drive ratio puts the blower at 13,000~ Rpms When I shift around 5700 and boost is rapidly falling off by 6200 if I hold out...

now consider this, limiting your engine to 5500 RPMS with a 144 blower may produce 480~ Horsepower on your engine. The bigger is better rule does NOT apply here... and ALL you have is BIG BIG BIG on your combo... By REMOVING the blower your engine would like to spin way past 5500~ maybe closer to 6500-7000 which would produce ALOT more PEAK horsepower than with the blower... simply because of the better breathing / high rpm band capable without a blower attached... thus adding the blower may actually hurt your performance.

My recommendation? Either step up to a bigger blower.... Or step up to a nice N/A carb setup and a little Go-juice. A 144 has no place on a high revving 383... trust me, bad idea.