Baja226sport

iTrader: (28)

FIRST......I know the 174 is not ideal. I know if you overdrive it, it gets hot as hell and you lose power. I never run WOT for long periods. The wife won't allow it. I am not cutting the hatch for anything bigger, Ii do not have the means to buy anything else.

Sooooo...anyone telling me not to bother.....I already heard it all.

who has put these on a 502? What heads were you running? What pulley? What psi? Anyone dyno???

Please, any and all info is appreciated if you have done this.

Griff

I haven't done it on a 502, but I did run almost 8# of boost on my 525SC with the 177.
All the 174/177's are overdriven. I was at about a 2.5:1 overdriven.
The stock 525SC was 5.5# of boost overdriven at a 2:1 ratio. Bottom pulley was 7" and top was 3.5.

I would guess at 2:1 you'll see about 4-4.5# on a 502. Just change the lube at least every 50 hrs. I changed mine every 25-30 hrs.

90viper

iTrader: (1)

Search 525sc. Since I am putting a pair of 525sc sealed with 97 hours in my Scarab Vioer wanted more info. I do not remember who but will try to find posted a lot of info on 525sc. Have not seen a post in a long time on jet mech. Is he ok? Never saw final number on his vioer.

89Force235

Hi, if you haven't already, take a look at my thread. I'm doing a 174 build too. I'm taking some punches and a few of them are well deserved; however, there's a lot of info there. Including some on some larger cube builds with 177s and 174s. Also, if you'd like I can share with you B&Ms original technical brochure by email..

Thanks,
Travis

http://www.offshoreonly.com/forums/d...t-project.html

Baja226sport

iTrader: (28)

His Viper was running 102 mph last summer! he's busy building a bad ass mustang right now. Sometimes I wish I still had my viper! 525 SC info is close but I am really looking for boost #'s with the 50+ more cu in I have with actually 509/516's

Baja226sport

iTrader: (28)

I'm trying to read through this but damn it is giving me a headache!!! You have rectangle port intake??? I have now owned 4 different 174 blowers. None have had a rectangular intake. Infact you can't even buy one from summit or jegs. They sell as "will fit either" they are a lot closer to oval.

ezstriper

from what I was told at holley tech, the 174 was a low rpm deal on BB apps, the 177 was the 1st HP type that they made both intakes fro a BB, most 174 were for SB use

89Force235

Mines definitely a square port. That said, I have one of the oldest 174s I've seen. The rear mounting bolts and the front gear case/blower drive cover is a little different on mine....

MILD THUNDER

iTrader: (3)

In my old B&M tech book, they recommend running no more than 5lbs of boost with the 174 blower, on a 454ci due to heat. On a 502, that should be about 3lbs, if you were to take their advice.

In order to make about 5lbs on a 502 (many other factors to consider besides cubic inch though), you'll probably have to drive the 174 blower around 2.3:1. So, if you are seeing say 5300RPM with the engine at WOT, the blower will be turning 12,190 RPM.

Now, the appropriate sized roots blower for a marine 502, would be about an 8-71. To make the same 5lbs of boost, you'd be around .90:1 ratio. So, at 5300 engine RPM, the blower would be turning 4,770 RPM. The small 174, will be turning roughly 7500 more RPM at wide open throttle. Thats an extra 123 revolutions per second! See where the heat comes from?

At 12,190 blower rpm, the rotors are turning 203 times per second!! The 8-71 rotors, would be turning 79 times per second.

Now, on a street engine, or tow vehicle, at 2,000 engine rpm, the 8-71 rotors would only be turning 30 times per second, where as the 174 , will be turning 76 times per second. There is certainly advantages to small highly overdriven blowers, and thats from about idle, to midrange rpm, where they can produce more low rpm torque, due to less leakage time. But for a boat, the benefits of a larger blower, far outweigh any advantages to the small blower.

I know you have heard it all, and really don't want to hear about the 174 being too small for your 502. But, I thought I'd at least make a post for others who might find the info interesting. I've been there and done it with the small blowers, and would never go back to a 174/177, 250/256 on a marine big block. If hatch clearance was my issues, I'd look at a procharger with a good intercooler.

Good luck with the project.

MDGperformance

We have done several 174/177 blowers on 502/500hp motors not ideal but it will work at around 4-5lb boost it will give you an extra 100hp or so,need to richen up the carb and keep the timing around 28-30 also 91-93 octane .The motors we did had the stock 8.6:1 compression and the stock merc hp500 cam