525sc Rebuild
 

I have twin 525sc motors that I'm planning on rebuilding this winter. Would speed pro forged L2399F pistons work for this project? Reason being I have 2 new sets available to me if I can use them. I have new eq320 heads and going hyd roller. If not what piston should be used?

I rebuilt my 525sc with .060 over 2399 pistons. I used a 134561 flat crane cam, hp500 heads. Stock pulleys. I made 572hp@5600. Runs strong. Got 60 trouble free hours this summer.

the 525sc came with 7.5-1 compression ratio,the bump in compression from the L2399f piston will help wake it up,the eq 320s will also be a big improvement in power.with the right hyd roller cam you will have good reliable power.i think you will like the end result.

Thanks everyone.. What compression ratio should be used, 8.5, 8.8? I have stock pulley and the smaller pulley. Also running intercoolers.

i built a pair of 454s for a member,compression ratio of 9 to1,afr 305 heads,bob m cams and 177 blowers that made 690 on the dyno,ON 89 OCT FUEL.the cam,s were mild due to a wet exhaust.

The eq heads have 119cc chambers and speedpro's website shows 8.84 but does not say what thickness head gasket.
http://www.powerforgedpistons.com/pdf/applications.pdf

Mine made 572hp. How much of the 115hp would you attribute to the afr heads vs my 088?

If the heads are aluminum good for at least 9.5 compression. Make the setup conservative with rich fuel (under 12) and light timing in the 30-31 area.

BT

That piston has a 13.8cc dome. With the piston in the hole .010, a .053 head gasket, youll be about 8.9:1 with the .060 overbore.

I will be .030 over, so I think 8.8:1 with .010 in the hole and .053 head gasket. I have daytona sensors ignition boxes, can I still use the 525sc curve at that compression?

I dont know where i got the .060 overbore. Didnt get my coffee. In yet. But yea, 4.280 bore will be slightly less.

You could use the stock 525sc map, or a custom 2d map, or 3d map, etc. Lots of options

I played with timing from 31* to 34* all in. My motor made the best power at 34* and also had the lowest EGTs. My builder did not want to run more than 34* though.

Stock 525sc ran 34 or 35, cant remember. I'm running 35* at 6000rpm, 34* at 5500RPM, 32* at 5000RPM. 468, 420 blower, 8.5-9lbs boost. -9 heat range plugs, non projected tip. EQ 320 Iron heads.

The stock timing is 35 at 4500.

the pair i did have the t bolt 4 with v6 modules and 34 deg total advance.they have a custom race tek piston.the combination of parts seemed to work out well.

Only thing Id be wondering , is the use of the intercooler with this setup. The 177 is gonna be small for a hot 454 with good heads and cam. If i recall, on the engine mike tkach is talking about , those blowers were at 115% overdrive to make about 5lbs on my old engines and the ones hes built (my old blowers). They didnt have intercoolers.

I know when i added the intercoolers under my 420 blowers, i had to really increase the overdrive to get the boost back. The core is an airflow restriction. I am assuming you will have to go with a pretty small upper pulley, just to get to 5psi on that setup. Prob still better than not having an intercooler at all though on that setup.

Couple things Id consider. Making sure you have enough carb, so your not handicapping the blower. They dont like to have inlet restriction. The 177s are not teflon tipped, and i would make sure the blower is tight and fresh. If the rotor to case clearance is excessive, this will further exacerbate the issue.

Also, keep an eye on the rear bearings. The rear of those blowers use a crankcase, and known to get fuel diluted when the seals wear.

With that being said, i dont think 650hp will be too hard. Should be a nice running setup.

if i remember correctly we were at 4 to 5 lbs boost.the carbs were singel 1025 cfm 4150s.joe brought up a good point about the rear bearings on the 177s,,they do need to have the lube freshened every now&then.

Sounds about right. I wanna say, it had a 7 inch bottom pulley, with a 3.25 top , but its been a while . Prob would need a 3.00 or 2.85 top pulley with the chiller to get to about 5lbs with the cam and head upgrade

I have a 7 inch bottom pulley and a 2.85 top pulley. The blowers are going to DMPE for rebuilds. The carbs are the 1050 dominators.

^^^ nice . Heard good things about Darren

Stock 525SC is 7" lower and 3.5" upper pulley. I ran a 2.88" upper and was just under 8# of boost with no chiller.

Max blower recommended blower rpm was 13,500 and I was close to 13000 at 5300 engine rpms.

I changed the front and rear blower lube every 30 hrs or so. The blower had about 500 hrs on it without being rebuilt.

Now that the short blocks and heads are done, it time to get cams ordered. I am shooting for a static comp at 8.7 or 8.8 to 1. Mike T. made 690hp with a Bob M. cam. Laz Mesa made 657hp with RHS heads and custom cam. Eddie Young has made power with his cam profiles for a 525sc. My question is how do you choose which one to go to and use? Or would the 525 efi cam be a better choose? I would like to maximize the efforts that Jim V did on the heads. All opinions are welcome.

I'll bring this thread back to life as I am going to be undertaking this task this winter...any updates on what you ended up doing and power you made??

Stewart