With a turbo 6000 should be God's plenty.
I have turned mine 6500 on nitrous, but I'm not the sharpest knife in the drawer either.
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| 225 rpm limit https://slantsix.org/forum/viewtopic.php?t=41205 |
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| Author: | jackdaniels [ Mon Jul 26, 2010 2:34 pm ] |
| Post subject: | 225 rpm limit |
Gentlemen, hello everyone. I have been reading about the 225 in this forum. I read a couple of threads about the limiting rpms in the 225, and how some say that is very restrictive and some say that you can squeeze more turns per minute out of the motor. Im doing some research and im trying to calculate every aspect of the motor before i start taking decisions and purchasing parts. My intention is to go turbo on my 225 but i want to build it for the street and strong enough for the strip. I started reading about the limiting rpms on the torqui 225 so my question is how far can i push the motor to still be on the safe side? ideas, suggestions, rules, and any other is more than welcome. Thanks |
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| Author: | Aggressive Ted [ Mon Jul 26, 2010 3:49 pm ] |
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Doc is your man on this one. The head will only flow so much..... There are many on this site that run turbo's. Send him a PM however, I have heard of them spinning 7200 rpm, but it is unnecessary when using a turbo. |
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| Author: | slantzilla [ Mon Jul 26, 2010 4:03 pm ] |
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With a turbo 6000 should be God's plenty. I have turned mine 6500 on nitrous, but I'm not the sharpest knife in the drawer either.
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| Author: | Shaker223 [ Mon Jul 26, 2010 4:21 pm ] |
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Ran 11's shifting at 4600 and Turbo66valiant runs 10's shifting at 5200rpm. Both with turbos. |
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| Author: | Doc [ Mon Jul 26, 2010 4:28 pm ] |
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There are a number of different issues at work here so we really need to figure-out which "limit" we are talking about. We all know that the factory 1 bbl carb is a big limiter, that is why many owners swap to a 2bbl or 4 bbl. The same goes with the factory cam and valve size / head port size. All this stuff "limits" the amount of "air" the engine can pump and that limits RPM & max horsepower. Air flow improvements are easy, compaired the machanical limits of inturnal engine parts, with connecting rods and con rod bolts being the weakest links in that part of the "chain". This is where the inter-relationships between the parts comes into play... like lighter pistons and connecting rods, to help reduce stress on the con rod bolts, crankshaft and bearings. Race engine designers run a lot of calculations on rotating mass, piston acceleration, max piston speed and side loads in order to get the maximum RPMs with good cylinder sealing. In the end, it seems like the engine "tops-out" when it looses combustion sealing or when piston speeds reach the speed of the fuel's combustion rate. (the piston will not move faster then the expansion rate of the burning fuel) In the real world of building high RPM Slants... I get to the point where I can't seem to keep all the fasteners tight.    DD |
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| Author: | jackdaniels [ Mon Jul 26, 2010 6:51 pm ] |
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One more time i am amazed by the info here. And to begin i think im asking a too broad question. My plan is to run the stock crank and the reason is because i read that it comes forged, from factory. My 225 is from a 1972 dart. Stock rods because i read as well that they come forged from factory. I read a topic here about shaving them (the beam side) and making them soft and nice, just to take away the roughness and stress points. Again, you can correct me if this is wrong and if my understanding of them being forged is correct. The pistons, i will order them from WEISECO, 8.4 or 8.5:1 static cr, aluminum forged to match the "bulletproof" bottom end. I believe i didnt direct my question correctly. And im really no interested in spinning my motor @ 7000 or 8000 rpm. I also think that 6500 is plenty and if i can shift somewhere between 5200 - 5600 that would be great. The turbo that i ordered will generate peak flow @ this mini band that i described. A little higher and it well start being inefficient. I guess my question now is, with my combo, will i be able to do that? I also calculated my VE @ 74ish % because ive read that slant heads are not the best air flowers out there. Im working in some bowl work, gasket match, port n polish but like i have read. Bigger is not better. Im looking into getting bigger valves as well and im looking forward to learn how to do that with your help. |
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| Author: | bigslant6fan [ Mon Jul 26, 2010 9:18 pm ] |
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5,000 RPMs 10 LBS of boost on stock rods,pistons ARP rod bolts,No problem.But,be sure to follow Doc's oil system mods,when he says to check the cam/crank passages to be sure their drilled completely through the oil pump feed,BROTHER,he isn't joking! The '73 block I'm building now wasn't drilled through,and I couldn't put a 3/16 rod in the passage.It kind of makes me wonder about the naturaly aspirated S/6 I blew up 7-8 years ago at 5,500 RPMs before I knew this forum,and never knew to check.Hmmmmmmmm
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| Author: | Brussell [ Tue Jul 27, 2010 3:49 am ] |
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I'm abit interested to know what range I can get out of a STOCK 67 slant 6 225. Atm I've got no exhaust and just the extractors and it's pretty loud so I'm not sure when to stop revving. I just stop at 3/4000. it's had a little bit of work port and polish, extractors, new igniton setup with new module etc. Thanks guys! |
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| Author: | Dart270 [ Tue Jul 27, 2010 5:45 am ] |
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You are safe to rev at least to 5000, but the motor might be done pulling at 4000. Lou |
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| Author: | Rug_Trucker [ Tue Jul 27, 2010 5:47 am ] |
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I have access to a cast crank motor. I to eventually want a turbo motor. I want to drive the wheels off it. Cast is much lighter. At the levels I am wanting ? I'm thinking it would be fine. I do want to use the 198 long rods. Slanters do we know what power the lightened cast crank can take? |
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| Author: | slantzilla [ Tue Jul 27, 2010 11:23 am ] |
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You'd have to mill the rods to make them work. The rods are much narrower in a cast motor. As long as you keep it from detonating the crank will be fine. |
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| Author: | turboram [ Tue Jul 27, 2010 6:05 pm ] |
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if you run my numbers 450-500 hp should be OK on a cast crank,as Ive beat on mine for several years and never had a problem. I'm acualy trying to break the crank but can't seem to hold a head gasket |
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| Author: | Dart270 [ Tue Jul 27, 2010 7:33 pm ] |
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Dang it, Nick, you're just not trying hard enough!  Most people here will never see a cast or forged crank motor be hurt by a buildup. I am moving towards the cast crankers for just the reason Rugtrucker says - they are lighter overall (35-40 lbs) and the crank on the late 80s ones is 16 lbs lighter by itself. Yes, you'll have to mill the big ends on 198 rods to fit - be careful to do this right as Doc had a side clearance issue. I have an '85 shortblock on the stand with new narrow K1 rods and Wiseco 3.445" pistons in it set at 0.005" outta the hole at TDC. Just need a good head now... Lou |
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| Author: | Rug_Trucker [ Wed Jul 28, 2010 5:12 am ] |
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I have access to a '76 or '77 cast right? What is the difference with the late 80's? |
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| Author: | Dart270 [ Wed Jul 28, 2010 5:54 am ] |
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Crank, block, and head are all a bit lighter from about 82-up. 76-77 will work just fine, though. Lou |
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