What is a good combo for turning high rpm?

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1lostsoldier said:
I reminded by my friends favorite saying,"Road racing makes a heroine addiction seem like a vague craving for something salty":toothy10:
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Now that's funny. :D

I don't have a lot of road racing experience, mainly parking lot zamboni stuff at this point. Back when I was younger I did a good amount of back road bombing, so I can have somewhat of a feeling for what you are saying. Steve, (autox), is a very good source for info, if not a bit modest.
Mopar Action's tech editor, Richard Ehrenburg (not modest at all), built a very competative Valiant, using mainly factory suspension, a Barton built 340 stroker (379?), W2 heads with a Rance F.I. It's backed by a Tremec TKO and a 8 3/4 rear with 2.45 gears.
I offer for your consideration that the small block Mopar has a couple of things the SB2 and LS guys wish they had, a fully skirted block and 6' rods.

Regardless of which way you go, keep posting, I am really interested in how you do.
 
The power band is what I was referring to playing with to get the shoft points les objectionable. Like you big block tho, you simply can't compete with a engine that can spin and make power in the high rpms. Winberg may have one in the stroke you have now or the 3.58 deal witht he small pin size. There's also some used ones for sale. Ryan at Shady Dell has some contacts for used racing parts. Might want to talk to him for leads, never mind his abilities.
 
Follow up on another post. How about your tranny ratios? Are they so the engine can be in it's sweet spot? Not being a road racer maybe you all will inulge my curiousity.
 
I thought I would chime in on this. My engine is an 8k RPM 340.

I would call it an old school build that relies on high RPM and high compression to make up for it's lack of cubic inches. It was a very expensive build with all the precision machining coupled with the cost of all the quality valve train components.

Now when we talk reliability we need to put things into perspective………

My engine is/has been very reliable but you need to realize that reliability and long life are not the same thing.

The high spring pressures and stress at 8000 rpm limit lifespan on some components.


So, reliability?………… Sure as long as you are replacing springs and pulling bearings every 2-5 thousand miles.




In other words……. Things that are not standard maintenance items on an engine that only turns 6-6500, become standard maintenance items on an engine that turns 8k+.
 
1968FormulaS340 said:
I thought I would chime in on this. My engine is an 8k RPM 340.

I would call it an old school build that relies on high RPM and high compression to make up for it's lack of cubic inches. It was a very expensive build with all the precision machining coupled with the cost of all the quality valve train components.

Now when we talk reliability we need to put things into perspective………

My engine is/has been very reliable but you need to realize that reliability and long life are not the same thing.

The high spring pressures and stress at 8000 rpm limit lifespan on some components.


So, reliability?………… Sure as long as you are replacing springs and pulling bearings every 2-5 thousand miles.




In other words……. Things that are not standard maintenance items on an engine that only turns 6-6500, become standard maintenance items on an engine that turns 8k+.
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Welcome back 1968formulaS340.:-D
 
If you need to stick with the 318, I would use a lightweight 3.58 crank, change the pistons and do some oiling mods.
You won't get much power at 8000 with those heads but you can probably get them to pull to 7000rpm with maybe 400-500 rpm overrun before power falls off fast.

If you can change heads, simple W2's will allow what you want, with TD rockers you'll have stable rpm.
What do you use for fuel?
I'm sure you can get some usefull high rpm power and reliability with the sb mopar. If you need to save weight, Indy's got a 210cnc port in their sb heads that works really well. You can use a victor intake if hood clearance is an issue. Keep compression as high as you can with whatever fuel your running and pick a cam with an rpm range of about 600rpm lower than the max rpm you want to turn.
You could use the 318 crank but I think the extra TQ through the rpm range will make the car better even if you don't hit the 8000 mark.
Brian
 
1lostsoldier said:
Any recommendations for a crank?
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I use Scat. I sell Scat. They are one of the best lightweight cranks for the money. I think they are 1500.00.
I have one that's balanced to Scat I beams and Ross flattop pistons, don't know if you'd be interested. I'm not trying to sell you on that though...
I just feel that the extra stroke over the 318 crank is worth it. You will need a solid roller cam and lifters to run that rpm for sure. Once you get a good combo to spin that high and make power up there, you'll have alot more than 400HP. I would figure closer to 550HP and maybe more.

So you could put W2's on the 318 to keep HP down...I guess?
 
ou812 said:
So you could put W2's on the 318 to keep HP down...I guess?
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No valve to 318 bore issues with W-2's?

How much RPM is the current crank up to? What HP with that RPM?

So at minimum: cam, lifters, W-2 heads (to work with current pistons?), T/D rockers for quality and to fit W-2 geometry?
 
1lostsoldier said:
Right now I'm running 318 with a stock forged crank, eagle forged 4340 I beam rods, speed pro forged flat top pistons 3.91",RHS x heads with 2.02i 1.62e and mildly ported, Harlan sharp 1.5 roller rockers,6.1 hemi beehive springs, Crane hydraulic roller cam 300/308 .548/.558, eldebrock victor intake, 4150 650 carb, milodon road race oil pan, 2 quart oil cooler, 2 quart accusump and msd distributor and 6aln box.

right it pulls pretty strong to 6700 then it just gives up

thanks for any help.
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Just a refresher of my current setup
 
ou812 said:
I just feel that the extra stroke over the 318 crank is worth it. You will need a solid roller cam and lifters to run that rpm for sure. Once you get a good combo to spin that high and make power up there, you'll have alot more than 400HP. I would figure closer to 550HP and maybe more.

So you could put W2's on the 318 to keep HP down...I guess?
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From everything I'm told about getting more rpm out of an engine I always hear not to increase the stroke because the longer the stroke the faster the relative piston speed which is harder on parts. Is this not true?
 
I am just going to throw my opinion in here....I have seen 7500 numerous times with a 318.

I didnt see a windage tray in your engine specs...or a HV oil pump.

In your situation, I would decrease the cam duration to the 220-230 @ .50 range....around 262* advertised..over 300* is not good for sustained high RPM.....your cams lift is adequate.

At 100% VE a 318 requires 630 cfm, but for your higher rpm desires

I would get a race prepped Holley 750 MS....

For your high rpm pulls where you want to not have to shift.....I agree with another person who replied....decrease your final drive ratio.... 3/4 less of a rotation in your driveshaft will give you longer gear duration.

I understand the acceleration from slow speeds is less snappy, but everything is a sacrifice or trade off.

Can you reduce any more weight or is it race spec already?



:read2:
 
1lostsoldier said:
From everything I'm told about getting more rpm out of an engine I always hear not to increase the stroke because the longer the stroke the faster the relative piston speed which is harder on parts. Is this not true?
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It all depends on the parts and combo. The rod ratio is still very good, and I've run my 360 up to 8000 more than once with no ill effects and I was running stock rods!
So lighter components, good oiling and good oil control will get you reliable rpm regardless of stroke.
Like I said, you can keep the current crank but it will be a weaker combo than the 3.58 stroke.

Indy heads have the valve centers moved towards the ex. side of the chamber so this will reduce shrouding.
 
Prine said:
I am just going to throw my opinion in here....I have seen 7500 numerous times with a 318.

I didnt see a windage tray in your engine specs...or a HV oil pump.

In your situation, I would decrease the cam duration to the 220-230 @ .50 range....around 262* advertised..over 300* is not good for sustained high RPM.....your cams lift is adequate.

At 100% VE a 318 requires 630 cfm, but for your higher rpm desires

I would get a race prepped Holley 750 MS....


Can you reduce any more weight or is it race spec already?



:read2:
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Yeah it has a hv oil pump and windage tray and scraper and the crank has been knife edged it also has most of the standard road race oil mods. You sure on the cam spec? I had a 280 advert duration cam in it before and it only pulled to about 6k before it fell flat.
I've played quite a bit with different carb setups with my daytona stand alone wideband datalogger. had a speed demon 750 on it and its mid range 4k-5.5k was never as strong as the 4150 hp series holley 650 and the data log shows my a/f at ~12.5 to 1 at 6700rpms.

I guess I should clarify better that my motor will and has rev passed 6700 many times. Ive logged a couple 8k hits as well but it drastically loses power pass ~6700. I believe its the heads holding me back and I'm not real comfortable reving pass 7k with the stock crank even though is forged.

Weight wise I'm running a full 14 point cage and all original steel metal so I could easily shed some weight with a fiberglass front end, doors, bumpers, deck lid and maybe even going to aluminum heads. BUT i like running a real steel body and race fiberglass always looks like garbage up close.
 
You're getting away from my comfort level in terms of what I would normally build but I dont think I'd put a Scat peice into it. By the time it's trimmed and lightened it's still not as good as a purpose built billet. It's defintaely cheaper, but I don think I'd do it. The longer stroke does make for faster mean and peak piston speeds which means rods, pistons, and pins all need to be the best quality. It also means you need to have ports that will flow what it's going to need and a cam to work with the heads. I dont think the RHSs in any form could do it, even on a 318. I'm curious if you've tried a larger rated 4150 series carb on the 318? I'm not a fan of Demons in any form due mainly to manufacturing defects that are still overly abundant. But I'd be curious if something like the Street Avenger 770 might not work well on it and get it to make power higher.
 
We went the other way with the engine in Tim's car. It is a 427 inch small block with a 4.125 stroke. It has peak power at 5800 rpm so the power is made in a different part of the curve. I can't see building a 8000 rpm engine for $7000 unless you already had all the parts on hand. That 427 engine cost about $18,000 to build and that was with me doing a lot of the machine work at no cost. Had it been built by an engine shop it would've cost about $20,000.
 
i run a 7000 rpm limiter in my 68 cuda... i had it set at 6 and would hit it so easy. i had a 7500 chip and hit that as well. its like to rev.

but for road racing with high rpms all the time i doubt it would hold together
 
AndyF said:
We went the other way with the engine in Tim's car. It is a 427 inch small block with a 4.125 stroke. It has peak power at 5800 rpm so the power is made in a different part of the curve. I can't see building a 8000 rpm engine for $7000 unless you already had all the parts on hand. That 427 engine cost about $18,000 to build and that was with me doing a lot of the machine work at no cost. Had it been built by an engine shop it would've cost about $20,000.
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Uh oh....I hear crickets now! Guess it's GM eh??
Hey Andy, how the heck did you get so much $$$ in that engine? I don't think I read the whole build you posted so forgive me if I missed something.
 
That is just what the total cost was for parts, machine work and final dyno testing. Nothing super trick in the engine, but it does add up. I kept a spread sheet and filled in the cost of each part. The total spent was over $19,000 for parts and machine work but a few things were done twice so I rounded down the final number to about $18,000. I didn't include anything for my time though and I spent a lot of hours on the CNC mill removing material. So if the engine had been built at a professional shop I'm pretty sure the final bill would've been over $20,000.
 
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