Turbo 300 '67 Stang

brandoncw

Well-known member
Hi boost gurus, i am going to build a 300 for a 67 mustang. The reason i picked a 300 is simple, i had one. And cause i wanna have that "wow" factor, nobody looks twice at a stock motor or a 302 swap. I have a few questions.

The biggest is, how much abuse can a stock crank take if balanced and the whole nine yards?
What kind of power would i be looking at from my build combo? ( list of parts below )
Will an 8.8 rear end hold up to the engine?
Will a tremec TKO 600 ft/lbs tranny hold up?


Parts/Mods list:
Block bored .030 over (cyl 5 was pretty rough)
stock crank (maybe) if not then a forged crank
Hx35 turbo, MAX 20 psi. Will use 10 on most occasions, just 20 for a track run or to race someones lawn mower (internal waste gate welded shut, external waste gate and blow off valve will be used instead)
Fitech EFI Power Adder 600 hp system (rated at 650 hp for regular fuel, rated at 30% less for E85)
Port and polished 1985-86 carb head W/ 1.94 intake and 1.6 exhaust valves
Scorpion roller rockers 1.73 advertised lift ratio
Custom pistons (dish will be determined by Combustion chamber volume)
Molnar tech rods
and a custom crower cam https://www.dropbox.com/s/qufkzkwyxoz8o ... m.jpg?dl=0
Offenhauser intake
And either a runner style turbo header or efi manifolds with pipes run underneath and around to drivers side ( all depends of space available
Inter-cooler will be used

Thanks for your guys input
 
The Crower turbo cam is designed to make big torque numbers from 2000 to 3500 rpm and is a good match for a HX35 turbocharger.
With a good exhaust system as you are planning on, it would be possible to make 600 ft lbs of torque @ 20 lbs of manifold pressure.

The crankshafts usually fail from torsion vibration above 6000 rpm.
Turbocharging is easy on engine components and the cast iron crank should be OK with low rpm high torque operation.
You can help the crankshaft strength by making a larger rod journal radius (Fillets) when the crank is turned for the 2.100" journal connecting rods.
 
pmuller9":331xjujj said:
The Crower turbo cam is designed to make big torque numbers from 2000 to 3500 rpm and is a good match for a HX35 turbocharger.
With a good exhaust system as you are planning on, it would be possible to make 600 ft lbs of torque @ 20 lbs of manifold pressure.

The crankshafts usually fail from torsion vibration above 6000 rpm.
Turbocharging is easy on engine components and the cast iron crank should be OK with low rpm high torque operation.
You can help the crankshaft strength by making a larger rod journal radius (Fillets) when the crank is turned for the 2.100" journal connecting rods.
Interesting, I figured boost would put a lot more stress on the parts.
I was talking to one of the sales representatives about the rods and their offset. Im not really sure which wa they are offset, are the off parallel to the rotation or perpendicular? He was saying it can potentially put too much stress on the rods. Is there a way I can offset grind the crank to counteract the offset of the rod? And is there a specific orientation I should install the rods?
Common sense tells me 600 ft/lbs sounds like a bit much for an 8.8 rear, even if its built.
 
The way a turbocharged engine builds cylinder pressure is a lot smoother than a naturally aspirated engine and certainly softer than supercharged or Nitrous so the impact loads are less.
It will of coarse create more torque on the crank and more downforce on the crank, rods and main caps. It just doesn't hammer the bottom end
as badly. That is why you see a lot of these turbo builds living with stock components, at least for a while.

I have measured BBC rods anywhere from .030" to .060" offset. Not sure what the Molnar rods will be until you get them and measure.
They are offset to the side of the beam or to the front and back of the engine.
They operate that way in a BBC meaning there is no problem with stress on the rods.

The one concern I hear is that the piston in the BBC is also offset and somewhat centered over the small end of the rod but the piston in the 300 six is directly over the center of the rods big end and slightly offset over the small end which might allow the piston to rock sideways.

What they forget is that the width of the small end is wider than the big end for that reason and with a .990" pin there is no way the piston can rotate sideways along the length of the piston pin.
Besides take a look at what .060" looks like compared to the diameter of the piston.

Not sure which drivetrain component will be the weak link. The only place that will be a problem is on the track with good tires and traction.
 
pmuller9":22u0ucav said:
The way a turbocharged engine builds cylinder pressure is a lot smoother than a naturally aspirated engine and certainly softer than supercharged or Nitrous so the impact loads are less.
It will of coarse create more torque on the crank and more downforce on the crank, rods and main caps. It just doesn't hammer the bottom end
as badly. That is why you see a lot of these turbo builds living with stock components, at least for a while.

I have measured BBC rods anywhere from .030" to .060" offset. Not sure what the Molnar rods will be until you get them and measure.
They are offset to the side of the beam or to the front and back of the engine.
They operate that way in a BBC meaning there is no problem with stress on the rods.

The one concern I hear is that the piston in the BBC is also offset and somewhat centered over the small end of the rod but the piston in the 300 six is directly over the center of the rods big end and slightly offset over the small end which might allow the piston to rock sideways.

What they forget is that the width of the small end is wider than the big end for that reason and with a .990" pin there is no way the piston can rotate sideways along the length of the piston pin.
Besides take a look at what .060" looks like compared to the diameter of the piston.

Not sure which drivetrain component will be the weak link. The only place that will be a problem is on the track with good tires and traction.

Well, i suppose i could always find out, ive got a good 31 spline axle laying around. If it grenades, then an 8.8 is too weak :LOL:

Update: I bought a set of of the Scorpion roller rockers today
 
What main bearings and rod bearings do you guys recommend

Molnar Tech suggested i use King Bearings CR807XPN rod bearings with their rods. and i assume i can trust their opinion with the quality of their products.

But i can only find Clevite, Sealed Power, and EngineTech main bearings. Are any of these good quality? I seen a review on clevite rod bearings stating that he wouldnt even use them in a kids bike even if they fit, so id assume their manufacturing standards would be the same for mains as well.
Is there another manufacture that i am not finding?
 
brandoncw":1nbzu15w said:
drag-200stang":1nbzu15w said:
Summit racing has them.
i found the king rod bearings, but i cant find mains made by them, if they even make them
They have king main bearing MB7750S1050 that fits 66-93 300 that ships from factory oct 15...Not sure if it would fit your crank or not.
Best to see what the 300 experts say.
 
drag-200stang":291xr3cv said:
brandoncw":291xr3cv said:
drag-200stang":291xr3cv said:
Summit racing has them.
i found the king rod bearings, but i cant find mains made by them, if they even make them
They have king main bearing MB7750S1050 that fits 66-93 300 that ships from factory oct 15...Not sure if it would fit your crank or not.
Best to see what the 300 experts say.

Sweet thanks. They should fit as i am not having the crank main journals changed, just Polished up good to get the very light scratching out.
 
Being a light car, the TKO and an 8.8 should hold up fine. The TKOS aren't known for high RPM shifting smoothness that actually goes in the 300s favor. You'll want a clutch big enough to handle the torque is the only possible weak link I see, if you're using a Mustang bellhousing that doesn't accept the larger truck clutch sizes.

King bearings are very widely used in race builds. I've seen Clevite bearings hammer out under high load turbo applications where stock bearings live at 3x the power. Even their claimed harder H series.

The HX is a little small for a higher RPM or HP build, but it should give very nice midrange power and make a very fun driver.
 
guhfluh":2ow9smas said:
The HX is a little small for a higher RPM or HP build, but it should give very nice midrange power and make a very fun driver.
I have thought about that, If i ever decide to go further i might upgrade turbos and camshaft.
From what i read, the smaller the turbo to less aggressive cam you should get, the the bigger the turbo the more aggressive you should get, is that true?

Im also looking for valves, SI Valves has the ones i need but I dont have a debit card, The stock valves have a 0.342" stem diameter, but the chevy valves im looking at have very close measurements of 0.341" stem diameter and 4.910" stem length, Will these work with the 300 stock valve guides?

UPDATE: apparently SI sent the valves without my knowledge (i thought i had told them to hold off for now) and are arriving TOMORROW!!! luckily i can just transfer money to the person that will receive them for me after they pay for it via check. Little irritated but not a big deal.
 
brandoncw":q47q2q2b said:
From what i read, the smaller the turbo to less aggressive cam you should get, the the bigger the turbo the more aggressive cam you should get, is that true?
Yes. The larger turbo needs an engine that pumps more air to match the operating range of the turbo's compressor.
 
Found a thread on making sbf harmonic balancers work with the 300, this bring to question, would a fluidampr balancer help reduce torsional vibrations significantly enough to run higher rpms?
 
If you can stick with the si valves your probably better off. The longer Chevy valves will require some careful valvetrain measurements, shimmed or adjustable rockers pending on the head. As well custom length rods to keep geometry happy, and obviously longer springs with hardware.
If your looking for revs down the road it gets expensive. Heavier springs for the larger(heavier) valves with boost, heavy wall and or thicker pushrods (as pushrod defection with the extremely long rods gets crazy) The high ratio rockers doesnt help, more food for thought.

The 8.8 is tough, if your worried remove the pinion crush sleeve and install a pinion shim kit. There are cars/trucks pushing a lot more to the pavement than we probably ever will with the 300’s. Doesn’t ever hurt to throw a bearing kit to the diff for the $$$.

I’m sure someone will chime in if I’m completely out to lunch with any of this, happy building.
 
sthorvictor":a0wiim2v said:
If you can stick with the si valves your probably better off. The longer Chevy valves will require some careful valvetrain measurements, shimmed or adjustable rockers pending on the head. As well custom length rods to keep geometry happy, and obviously longer springs with hardware.
If your looking for revs down the road it gets expensive. Heavier springs for the larger(heavier) valves with boost, heavy wall and or thicker pushrods (as pushrod defection with the extremely long rods gets crazy) The high ratio rockers doesnt help, more food for thought.

The 8.8 is tough, if your worried remove the pinion crush sleeve and install a pinion shim kit. There are cars/trucks pushing a lot more to the pavement than we probably ever will with the 300’s. Doesn’t ever hurt to throw a bearing kit to the diff for the $$$.

I’m sure someone will chime in if I’m completely out to lunch with any of this, happy building.

Well the SI valves are in and they look pretty good. Cloyes gears arrive tomorrow, rockers and my FREE :wow: summit hat arrive Thursday
 
pmuller9":1won2hd2 said:
I didn't get a free Summit hat in my last order. :cry:
I must be special. :nod:

On a more serious note, i decided i need to save a little bit of money until my bonus comes in so i can buy a reliable truck, my high mileage (over 350k on body unknown on engine) is not going to go on a 1700 mile drive, I really dont want to get stranded and be considered AWOL. That would be a bad time. so buying parts will be put to a halt for a month or so until i buy a new vehicle. Adult decisions suck :cry:
 
I have a feeling it is a bit of a stretch, but would this build have enough ponies to hit 200 mph??
http://www.tremec.com/calculadora.php i have the setting set to the Magnum 2.97 trans, 4.56 gears, 28 inch tires, and 5500 rpm ( thats about where i expect my peak hp/max rev to be. says in 6th gear i would be doing damn near exactly 200 mph :unsure: I think id have too much drag on the car and i wont have enough power to get nearly that fast. Maybe ill have to go full send and ramp up to a better fuel system and 35 psi :LOL:
 
The valves and pushrods came in and look quite nice. Maybe ill have to get a clear valve cover so i can look at em while its running :LOL:

Any how, im still working on putting all my part ill need in my shopping cart on summit. I am hung up on pushrods right now. Do i need 3/8 chromoly rods or 7/16 dual tapered rods?? And what length push rods for these rockers and an 85-86 head?
Thanks a bunch for your guys help. Just as much your build as it is mine at this point.
 

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