29scarab

MY engine is finally almost done.My ECM was sent off to Mark at Precision .Need to tweek the mapping a little bit more on the fuel. Here's some specs on the engine but I have a question also.

509cid
8.9 static compression
Comp 600 lift on around a 114 degree lobe
crane hp gold roller rockers.
stock heads
stock Whipple with stock pulleys
Stainless Marine exhaust

Scrapped the fuel system for a single big electric pump and regulator.

His dyno pulls came up with about 630 HP. I will get the the dyno sheets next week.Those numbers seemed a little low to me. I thought the stock engine with Whipple was advertised at 625HP. It just seems odd to me that I'm only making 5 more HP than whats advertised with stock components. I know they probably have ideal conditions to get the numbers they advertise, but it makes a person feel like they wasted some of thier money .

He told me the fuel was conservative at the top end and I could probably go with a smaller pulley to raise the boost, but I'm wondering how much of a change I would get with more boost and how much harder it would be on the engine.

Any of you engine guru's give me some input here?? Any input on this would be greatly appreciated'

Shawn

stevesxm

well.......... seems to me , from the specs, that you are " there"

stock 509 na CAN make 500- 525 maybe with all the right stuff and conservative compression ratio.

your specs indicate a conservative compression ratio with a reasonably aggressive cam but no cylinder head work... so really you are buying yourself 100 - 125 hp with the blower at low boost... again , to me, about right. more fuel may buy you a bit IF lean but if NOT lean then will be net loss... the egts tell you this answer...

more boost will give you bigger numbers

bigger ports w/ more flow will give you bigger numbers yet again w/ the additional boost

but seems to me you are getting the bang for the buck you paid for...i.e the additional 100 + hp w/ the blower.

maybe im just missing something here...

MESABALANCING

I like how it looks it's wicked from the front. As far as power goes it sounds a bit low but remember if the map isn't there neither will the power be careful with the tune up you put in it but I think you're going to see low to mid 700s when you're done my MB700sc is our entry level blower engine and it's based on a similar combo with carbs and no intercooler my MB700sc make from 720 to 770 hp depending if it's a heavy or light boat I use slightly different cam and head runner volumes. Be patient I know you'll see 700hp when your map is right. Sincerely Laz

Smitty

iTrader: (1)

Here is some info from my motor for reference.

509 ci
Modified fuel rail with a regulator and fuel return line. 55 psi
Edelbrock aluminum marine heads with extensive porting on the exhaust side only.
Crane 731 roller cam 587 int 610 ex at 112
CMI headers
Whipplecharger w/intercooler
Max boost at 5400 is 8 lbs

Dyno'd at 775 hp at 5400 rpm 8 psi
At 6 psi I was at 5100 rpm making 690hp.

Based on my numbers and considering you have stock heads, I think 630 hp is not bad.

I must also caution you if you are running a stock Bravo drive, that you don't really want any more horsepower. If you get any higher then the weak link is the drive and it will grenade soon.

My only suggestion is to change to a smaller pulley and run it up to 5500 rpm. The stock injectors can flow enough fuel at 55 psi to allow you to get to 8 psi boost. If you do you should be close to 700 hp.

29scarab

Thanks guys,

I appreciate the input. From your input it sounds like the engine is where it should be. I'm going to most likely go with a different pully which should get me a little further up on the power side.

Anyone know where I can find a deal on a smaller pulley?

Again, thanks for the input. God I luv this board!!

Thanks,
Shawn

articfriends

iTrader: (1)

3 years ago when I dynoed my motor build before my current one I had similar #'s around 6 psi boost,I was also extremely dissappointed. I posted the dyno sheet for you to compare (its the lower ,wider one obviously). I only made 620 hp and 695 ftlbs of tq and that was with merlin heads on a 8to1 540. Boat went 3 mph SLOWER than it did with 8.75-1 502 with same blower ,pulleys,injectors and heads. I talked to Kip at Cam motion and he told me my timing was too conservative for a innercooled motor and that each 2 degrees more timing under boost would be 25-40 hp (if it didn't blow up). I increased base timing in boat 2 degrees and picked up 2 mph,increased it 2 more and picked up another 2 mph,added 3 psi boost (from 6 to 9) which effectively leaned it down closer to the "edge" and saw another 4-5mph. By all calculations I raised hp from 620 to around 730-750 with those small changes. I raised boost another 2-3 psi and it did nothing,I think the exhaust side of cylinder heads became a major obstacle at that point. The efi program Crockett had back then pulled 1 1/2 degrees of timing out for each # of boost and it was definately too conservative for a 8-1 motor. I think there is alot more left if you tune it more aggressively.I ran the more agressive timing and boost for 140 hours and pistons still looked pretty good (no signs of detonation) when I tore it down to freshen/upgrade it further. Keep in mind the blower can make a mediocre intake port and manifold flow like ports 50 % bigger but it still has to exhaust and big power gains will come from bigger exhaust flow #'s (like on the other Smitty's motor),good luck,keep us updated,Smitty

offthefront

iTrader: (1)

Smiity .... what block/combo gets 509 ?

articfriends

iTrader: (1)

Bored out 502. 4.00 stroke with 4.500 bore (stock 502 is 4.4670)

Smitty

iTrader: (1)

509Ci comes from a 502 bored out about thirty thousands of an inch.