Engine Rebuild Questions
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Engine Rebuild Questions
Well, I'm getting a fair amount of blowby, oil is spraying from the dipstick and no matter what I do to try and seal it / evacuate the valve covers, it still insists on coming out the oil dipstick.
I'm going to do a leakdown test this weekend, but just judging from how it's running, I'm betting at least one of the pistons is cracked.
So.. I'm looking at a rebuild, I want to keep it a 350, I'm on a ridiculously tight budget and had some questions. Current specs are in my sig. Looking to shift her at 6250 or so, with my ignition cut at 6500. I'll keep it simple and direct from here out:
1 - Recommendations on forged piston + compression? I was thinking of trying to run around 9.5:1.
2 - Stock L98 cam + new 1.6 ratio rockers sufficient? Or is it worth swapping out the cam on the L98 to get her to breath up top? (note: TPIS miniram intake)
3 - Shot peen and reuse the stock rods? At what power do they start to fail?
4 - Any recommendations or thoughts?
Thanx in advance!
I'm going to do a leakdown test this weekend, but just judging from how it's running, I'm betting at least one of the pistons is cracked.
So.. I'm looking at a rebuild, I want to keep it a 350, I'm on a ridiculously tight budget and had some questions. Current specs are in my sig. Looking to shift her at 6250 or so, with my ignition cut at 6500. I'll keep it simple and direct from here out:
1 - Recommendations on forged piston + compression? I was thinking of trying to run around 9.5:1.
2 - Stock L98 cam + new 1.6 ratio rockers sufficient? Or is it worth swapping out the cam on the L98 to get her to breath up top? (note: TPIS miniram intake)
3 - Shot peen and reuse the stock rods? At what power do they start to fail?
4 - Any recommendations or thoughts?
Thanx in advance!
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Joined: Apr 2001
Posts: 3,525
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From: Houston TX
What intake are you running that you are shifting at 6250? Even with the P-600B, if you are running a long runner intake, the show is over by ~52-5400. This may be part of what happened to the current engine.
When you do get it rebuilt, I would suggest getting it on a dyno and see where peak WHP is on the chart and shift within +200 RPM of that value. As food for thought, my old 355CID with P-600B, SR, massive heads/cam made peak WHP at ~5600RPM. Even with my current combo, peak WHP is at 6050.
Something to think about.
Aaron
When you do get it rebuilt, I would suggest getting it on a dyno and see where peak WHP is on the chart and shift within +200 RPM of that value. As food for thought, my old 355CID with P-600B, SR, massive heads/cam made peak WHP at ~5600RPM. Even with my current combo, peak WHP is at 6050.
Something to think about.
Aaron
Melting Slicks
Joined: Jan 2002
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From: Jackson MI
If you are looking to keep the 350ci I would look into SRP pistons and see what they have for off the shelf parts. Going to a 355ci wouldn't be a big price increase if that is what you need to get the right pistons. You may want to bore it out just to get a clean wall to work with as well.
If you are planning on reusing the stock rods then you can use the stock crank as well given the rods will let out before the crank. You may want to upgrade the rods though. Its cheaper to upgrade them than to let them break and take out an entire engine.
I would definately go with a new cam. Even a mild cam will give you a bunch more power with your setup.
I would go 9:1 on the compression if you are running 12# of boost.
If you are planning on reusing the stock rods then you can use the stock crank as well given the rods will let out before the crank. You may want to upgrade the rods though. Its cheaper to upgrade them than to let them break and take out an entire engine.
I would definately go with a new cam. Even a mild cam will give you a bunch more power with your setup.
I would go 9:1 on the compression if you are running 12# of boost.
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I've been shifting at 5300 or so, I haven't had the nerve to up the rev limiter and actually run her that hot. My intake is the TPIS Mini-Ram, the figures I have for shifting were basically what I gathered after talking to them on the phone after I did the install.
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Otherwise I was looking at the LPE.. Or is it even crazy to swap out for an LT1 cam? (over the L98?)
- nrml
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Joined: Apr 2001
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From: Houston TX
But WOW 12 psi from the P-600B at 5300RPM, I worked for years trying to get 11 psi. What size driven pulley are you using? The 2.4" is about max before belt angularity chews up any gains you may have gotten.
It may be that you are close to stock, so there is more resistance to the flow. I think you will see boost drop as you go to new parts (i.e. cam, heads, etc).
I would definitely not go below about 9.4:1 as I do not think you will see 12 psi on the P-600B.
Aaron
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Maybe the MRII will pull that RPM. It didn't for me (5700 peak power).
But WOW 12 psi from the P-600B at 5300RPM, I worked for years trying to get 11 psi. What size driven pulley are you using? The 2.4" is about max before belt angularity chews up any gains you may have gotten.
It may be that you are close to stock, so there is more resistance to the flow. I think you will see boost drop as you go to new parts (i.e. cam, heads, etc).
I would definitely not go below about 9.4:1 as I do not think you will see 12 psi on the P-600B.
Aaron
But WOW 12 psi from the P-600B at 5300RPM, I worked for years trying to get 11 psi. What size driven pulley are you using? The 2.4" is about max before belt angularity chews up any gains you may have gotten.
It may be that you are close to stock, so there is more resistance to the flow. I think you will see boost drop as you go to new parts (i.e. cam, heads, etc).
I would definitely not go below about 9.4:1 as I do not think you will see 12 psi on the P-600B.
Aaron
The pulley is: 3.5" .. I won't even dare put on my 3" pulley.
I can guarantee you that the PSI I see is a product of resistance and not amazing tuning. The car pulls like it's only making ~330rwhp or so.
Safety Car
Joined: Apr 2001
Posts: 3,525
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From: Houston TX
What are the IATs when you get up to that level of boost? I would have to think that when you are spinning that little blower to the tune of 12 psi that the IATs must be getting pretty hot without an IC. But... then again, you are nowhere near MIS (with a 3.5" driven / 7" drive) for that blower, so maybe you are still pretty safe.
If I had a bit more details on your engine combo, I could probably ballpark the FWHP for you. As a side note, I ran the old P-600B with IC on a 355 to just over 570WHP, but over the course of about 3 years. Those units are more than capable on the small near stock cube motors.
Aaron
If I had a bit more details on your engine combo, I could probably ballpark the FWHP for you. As a side note, I ran the old P-600B with IC on a 355 to just over 570WHP, but over the course of about 3 years. Those units are more than capable on the small near stock cube motors.
Aaron
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Melting Slicks
Joined: Jan 2002
Posts: 3,293
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From: Jackson MI
Would you happen to have a cam recommendation? I've searched the forums and there is a lot of reference to the compcam 218/230, but from what I can tell it's a tappet cam.
Otherwise I was looking at the LPE.. Or is it even crazy to swap out for an LT1 cam? (over the L98?)
- nrml
Otherwise I was looking at the LPE.. Or is it even crazy to swap out for an LT1 cam? (over the L98?)
- nrml
http://www.cmotorsports.com/engine/l...ft-design.html
Feel free to give comp cams a call and see what they say. It wouldn't hurt to call them a few times and see what the different techs say. The 218/230 114 seems like it will work pretty well, a little bigger probably wouldn't hurt either.
As far as the 12 psi thing, are you running cats on this thing? If so make sure they are not clogged. Something overall doesn't seem quite right.
Another sure way to get less boost and more hp to your car would be to get your heads ported or get some aftermarket ones.