Black Baja

Yes dyno sheets are all make believe the dyno computer randomly generates numbers and for somewhere in the $500 range you get a print out. Dam shame it costs upwards of $30,000 for something that is so innacurate.

ealesh33

I don't have all the answers, not even close, but i figured you would have some more answers then you do, as I thought you were an engine builder? i may be thinking of someone else but I thought I read you have been building motors for 30 years? I don't build engines, I know a little about a little but, but like I said I'm not a builder. What kind of builds have you done with 454's and what kind of power did they make? Is this the first 454 with a blower or 177 you have done in 30 years? I'm here for the same reason you said you were, I'm looking for data.

I mean if you take some figures into play like each 1 lb of boost equals 25hp, that's kind of a blanket round statement but it's also referring more so to a bigger blower then a 177. Also have to take heat into effect, and with a 7" bottom pulley to 3.25" blower pulley you are spinning the blower 12,923rpms, From general reading the 177 is a 13,000 max rom blower, but I can't say how factual that is, and if I recall correctly i think it was Joe that posted that somewhere. On a stock 525sc that blower spins roughly 11,200 rpms makes 5-5.5psi of boost and adds roughly 120-125 hp to the 420 merc platform which kinda supports or is pretty close to that 25hp per 1psi of boost theory. Now there comes a point where the blower is starting to generate more and more heat and I'm sure that hp per boost starts to fall off, that's just a theory though. so if we use that figure 25hp per 1psi of boost and I think tthat's a little generous for this blower spinning at that rpm, at 4.2psi of boost would equate to a 105hp. Based on that thinking then without the blower the motor is capable of roughly 586hp NA. I am very curious how close that estimate is honestly, as I don't have real data to back that up. I'm sure there may be some variables that I may not be considering

mike tkach

you are right,i don,t have the answers ,good luck with your build.

mike tkach

yep,dyno is not data,just hocus pocus,i guess that 65,000.00 dts dyno was really a waste of money and good for nothing!LOL.

MILD THUNDER

FWIW, the 525sc was not a 420 with a 177 blower added. It had the 420 cam, but was 7.5:1 static, the 420 was around 8.6:1 if I remember right.

The 13,000RPM max blower speed, is right from my 177 manual I had. Bottom line, while it worked suprisingly well in this case for what it is, the 177 blower was NEVER intended nor designed, to be on a 700HP 6000RPM big block. I dont care if its a 427, 454, 496, etc. Blower is outside of its design parameter. I've said it before, and I would be willing to bet a case of beer, that swapping that blower out for a 8-71 on this build, would be worth probably 50-75hp at 6000RPM, minimum, and still run on the same tuneup. Might see a slight loss in torque output in the 3000-3500 range, but the upper rpm power would be worth the tradeoff, to me at least.

From some data I have from B&M back when they were building, designing, and testing these blowers, a 250 blower, at 60% overdrive, had an intake air temp of 140* at 6000.. Increasing the overdrive ratio to 112% over, the intake temp climbed to 230* at 6000. What they found even more interesting, was that at 60% overdrive, the temps stayed steady at 140* at 3000RPM, as well as 6000RPM. But, at 112% over, at 3000RPM, the intake temp was 190*, and increasing to 6000RPM, rose another 40*, to 230. Point being, once you spin the blower faster, it simply heats the air. Reducing temp from 230*, to 140*, is very significant.

Also, during some testing with the 420 and 6-71 blowers, they also noted that going from 8% underdriven, to 15% overdriven, raised the manifold temperature 62*. I can tell you we ran a non intercooled 10-71 making 8lbs of boost at 3% underdriven, that peaked around 140* in the manifold. We also tested a 10-71 with a blower shop intercooler, with 10lbs of boost around 15% over, with a manifold temp of around 115*. Although, that blower was also looser clearanced, than the stage 3 10-71 that saw 140*. A tighter blower will make more heat.

So, here's my though. Forget static compression for a minute, forget boost level for a minute. Which engine do you think would be more tolerant to detonation. A 8.5:1 engine with 230* air being fed into it at say 5lbs of boost, or , a 9:1 engine, with say 130 air fed into it and say 7lbs of boost? What about cam specs? Long duration vs short duration?

IMO, blanket statements like it has XXX static compression, xxx boost, being the end all to whether or not its safe, imo, is flirting with disaster. Stick a small heat pump blower on an engine, coupled with a short duration early closing intake valve, a good amount of static compression, and lots of ignition lead down low, you better have some money put aside for an engine rebuild real quick.

Personally, dyno numbers are great, and do give you the option for the tune, and a good idea on what kind of power you are making, but they are not the definition of success. Success is when that engine that made a great number, stays together when the throttle is pinned to the dash for 30 miles.

ealesh33

Damn thought you were smarter then that, I guess your not who you make yourself out to be on here.

ealesh33

Mild Thunder - yes that's where my math came from on the 420, this is how I broke it down as roughly a 15-20hp loss taking the 420 down to the 7.5:1 compression ratio, then just made the difference between that and the 525hp the 525sc is rated. Come to a gain of roughly 120-125hp the blower is adding in that app. Like I sayd this is just estimated but it's probably pretty close.

ealesh33

Mild Thunder - I think it's a combination but cylinder pressure plays a big role as well from my understanding. . Like what if you tried to bump compression in this application and put a bigger blower on it, but left the stock cam in it? When that was discussed, it led to the cam profile doesn't bleed off enough pressure so the cylinder pressure would be too high and it would be a detonation monster. But in that scenarios intake temps should be cooler then with a 177. So to touch on the duration and overlap there would have to be an acceptable amount for the application to keep the cylinder pressure acceptable.

If I remember correctly anyway lol

mike tkach

i don,t make myself out to be anybody on here.with every post you remind me of a past member who thought he knew it all[like you] but really had no experiance[like you].my guess is you,like him won,t last long.good luck with your build.

MILD THUNDER

Can you explain why some engines can live at 8.5:1 with 10, 12, 15+lbs of boost on the same gas your engine uses?