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Blown 460 street motor

5878 Views 39 Replies 11 Participants Last post by  boss 9 howard
Hello everyone,
Like it says in the title, I’m in the very early phase of a blown 460 build. The motor will eventually go in a galaxie down the road but let’s forget about that for now. Intended use will be street driving, this motor won’t ever hit 6k rpm. Goal is to just have something cool and hit the 600hp mark without having to work the motor too hard.
Here’s where I’m at. I’ve got factory block, factory crank, truck rods, forged pistons (22cc dish), D0ve, custom ground cam from Scott @ Parkland Performance. ALL SHORTBLOCK COMPONENTS ARE AT MACHINE SHOP getting the proper work done to them. Using all ARP HARDWARE.
Blower setup is off a boat, nice tall manifold, dyers drive to match manifold. I pulled the blower off an old 6/71 Detroit and converted it to be slapped on a gasser.With the drive setup I have (6% over) should make around 5-7 psi boost with this blower. (It’s a small bore 6/71, came of a turbocharged motor)


here’s where I start to have some questions....
Realistically, for what I intend to use this motor for, will truck rods do the trick?
With a thick (.098) MLS head gasket I can get comp ratio down to 9:1, is that acceptable?? I’d be willing to use e85 as a fuel source.
Also, what am I going to need as far as carbs? Was thinking 2 750s, or should I do 2 850s??

remember, I’m not going to beat this motor. it’s never going to the track. I just want something that has Big power down low and I can tinker with on the weekends.

I will post pictures in a few weeks when parts start coming back from the machine shop.
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Will be interesting to see how the second opinions compare to the ones rendered during the cam purchase phone call.

SJ
used 2b RHP
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Just curious if there’s any blower people that have some input
Will be interesting to see how the second opinions compare to the ones rendered during the cam purchase phone call.

SJ
used 2b RHP
Yea I really just want to find an excuse to run the D0VE’s over the D3 heads. I like that they are already stud mount rockers and I don’t have to hog out that bump in the exhaust port.
I think it'll hit 600 hp easily, and I also think truck rods will be good. Here's why on the rods: Most rod and rod bolt failures are due to tensile stresses-pulling forces. Those are determined by rpm. Compressive stresses, which rpm also plays a factor in, are largely due to cylinder pressure. Fortunately, rods are MUCH more resistant to compressive stresses than tensile stresses. I foresee no problem with any rod putting up with 600 hp at low rpm, especially as long as you don't rattle the motor with detonation. Even then, rod-related failures would likely be because of oil getting hammered out from between the rod bearing and crankshaft, not the power being made.
1) A good (Scat, Eagle, Molonar, etc..) H-beam rod is cheap insurance.
2) You’re quench is going to be terrible with that head gasket thickness.
3) That blower is pretty small, if you spin it faster to get more CFM you’re consequently going to make more heat which will raise you’re IAT’s.
1) A good (Scat, Eagle, Molonar, etc..) H-beam rod is cheap insurance.
2) You’re quench is going to be terrible with that head gasket thickness.
3) That blower is pretty small, if you spin it faster to get more CFM you’re consequently going to make more heat which will raise you’re IAT’s.
I agree with the rods. I know it’s insurance, just after buying rods I’m at a price where I might as well get an entire stroker kit. And I was just trying to avoid spending any unnecessary money. Trying to stay within a budget sucks lol
As far as quench factor I’m aware of head gasket far from ideal. And I looked into this on a few other forums too see if people have had issues. Saw many threads on them being used with success, not really any thread where somebody was just like “yup, installed these .070 headgaskets. And now my motor knocks like a jehova at 9:00am” I have d3 heads also. Just my machinist has a few sets here, and dude thinks they are power killers unless you put a lot of work into them.
Blower is on the small side yes, but it’s what I have to work with. Current pulleys make it 6% overdriven. We will see how that works out when it runs. If it can make 5psi or more I’d be happy.

all good input though, very much appreciated. Still on the fence about what heads to run. just in my mind I fell like d0ves are more optimal to use if you have a choice between the two.
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i have a 871 blown 545 fuel injected motor and well.... big adventure here lots to consider if you want dependability go to clegg engine select a rotating assy that will be close as possible to no more than 10-5-1 according to there chart use the super cobra jet gaskets for the head and intake and UNDER DRIVE the blower unless you are racing, i run mine at 12 percent under and at a roll i can break a 31x16.5x15 loose plus remember you are essentially putting a big air compressor on top of the motor it is going to create allot of heat in the intake charge i have several post here somewhere on all that and some videos but keep in mind pulley ratio on a blower is only part of the over and under drive equation to usable cylinder pressure for the street i run 12 under on my big tire car rolling around squashing mustangs and camaros but for fri fun nights i change my blower pulley out for 10 percent over now here is the difference 12 under with 76 cc aluminum head 40 thousands gasket dish 9_1 pistons gives me 12-1 corrected cr now when i toss the smaller pulley on for 10 over and its only 6 teeth difference i run at around 14-1 , as far as carbs i went fuel injection its better and cost just a little more than a GOOD carb example 2 really well built 800 cfm blower carbs (yes there is a difference) 900 each by the time your done 2k in carbs fuel inj 2300
yes blower carbs are set up for "boost reference" your ignition system again 6btm or 7 series i run a 6al with a timing retard and a 3 step timing control distributors are set up different also you want you dizzy locked on a blower motor, and going back to the intake using the scj gaskets is a blower intake ports are huge and you need to match the ports if not u will have air leaks and that will cause a blower motor to bup and when it does you need to change the base gasket so allot to consider first step is get a good rotating assy from clegg they sell the scat assys also contact dave at badassengines.com / don hampton / if there is any other spacific question i may be able to help with let me know and i can tell you everything i went through and did
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THAT was the best roots blower response that I have ever read! Kudos for that information.
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THAT was the best roots blower response that I have ever read! Kudos for that information.
🤪
Gets dynoed Friday, curious how she’s gonna do
93154
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I just want to know how you're gonna keep it down to 600HP.
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I just want to know how you're gonna keep it down to 600HP.
lol it looks meaner than it is. Cam is pretty mild
I just want to know how you're gonna keep it down to 600HP.
1.25” primary headers 😂
1.25” primary headers 😂
You should give this article a read… while there’s is definitely power to be made, if you’re racing and want every 10th of a second to count then go right ahead. But for a street car where I just don’t want to deal with fitment issues and a big price tag cj manifolds will do the job.
We’ll here’s what we got, still a little rich. And battling oil pressure, idk why it’s so low. Changed pumps, restricted pushrods, mains @ .002, rods @ .0015. I’m at a loss why oil pressure is so lousy.
Cam is solid flat tappet, 224 intake, 240 exhaust, 112 lobe sep
93172
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This is at 2500’ elevation
Hello everyone,
Like it says in the title, I’m in the very early phase of a blown 460 build. The motor will eventually go in a galaxie down the road but let’s forget about that for now. Intended use will be street driving, this motor won’t ever hit 6k rpm. Goal is to just have something cool and hit the 600hp mark without having to work the motor too hard.
Here’s where I’m at. I’ve got factory block, factory crank, truck rods, forged pistons (22cc dish), D0ve, custom ground cam from Scott @ Parkland Performance. ALL SHORTBLOCK COMPONENTS ARE AT MACHINE SHOP getting the proper work done to them. Using all ARP HARDWARE.
Blower setup is off a boat, nice tall manifold, dyers drive to match manifold. I pulled the blower off an old 6/71 Detroit and converted it to be slapped on a gasser.With the drive setup I have (6% over) should make around 5-7 psi boost with this blower. (It’s a small bore 6/71, came of a turbocharged motor)


here’s where I start to have some questions....
Realistically, for what I intend to use this motor for, will truck rods do the trick?
With a thick (.098) MLS head gasket I can get comp ratio down to 9:1, is that acceptable?? I’d be willing to use e85 as a fuel source.
Also, what am I going to need as far as carbs? Was thinking 2 750s, or should I do 2 850s??

remember, I’m not going to beat this motor. it’s never going to the track. I just want something that has Big power down low and I can tinker with on the weekends.

I will post pictures in a few weeks when parts start coming back from the machine shop.
With stock rods and crank you will have a grande you will probably double the tork and that is the monster
Thanks for the details. May I ask you which forged pistons you ended up using?

Also, on the cam - this cam of yours is somewhat similar to the Thumpr cam - but you are running a much larger lobe separation angle. The Thumpr has 107 and you are running 112. I guess that results in less overlap. Any thoughts on this end?

Rectangle Font Parallel Screenshot Technology
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Thanks for the details. May I ask you which forged pistons you ended up using?

Also, on the cam - this cam of yours is somewhat similar to the Thumpr cam - but you are running a much larger lobe separation angle. The Thumpr has 107 and you are running 112. I guess that results in less overlap. Any thoughts on this end?

View attachment 93564
Yes, lower Lsa with a boosted engine means you will end up losing some boost out the exhaust (overlap), not ideal. People bash the thumpr cams, but you will make good power and torque and have that sound you’re looking for still
Pistons I used were icon 15cc dish
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