300 at the wheels and idles smoothly?
Just asking, but what does the car run that has 300 RWH and at what weight?
Prove me wrong, but I feel a breeze under my shorts.
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| A misunderstanding about power https://slantsix.org/forum/viewtopic.php?t=41178 |
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| Author: | Blackbyrd72 [ Sun Jul 25, 2010 5:05 pm ] |
| Post subject: | A misunderstanding about power |
Ok, I kind of got excited and apparently stuck my foot in my mouth in another thread on this board when I said I had just bought an NA slant 6 thats supposed to make 321 hp. From what I read on this part of the board, 250 is max for naturally aspirated. So does this mean that the cam and the engine built around it are really supposed to be used with a turbo rather than the short ram Clifford 4 BBL manifold setup? Also the cam specs seem really mild on the build sheet, although the rest of the engine work looks impressive on paper, with reciepts for 1500 U.S. worth of machine work alone. All from a reputed, well known shop. There was an awful lot of headwork done on this thing, including oversize stainless valves , porting and polishing , and shaved .100, All the major components were magnafluxed, the wall thickness of the block was checked to ensure it could be bored .100 over. rods (from a 198) and offset ground crank , new custom forged pistons , all balanced and blueprinted, basically no expense spared on the build. About 3500 U.S. was spent on the engine in total. I can go get the sheet with the exact cam specs tomorrow, they are with the car I installed the ingine in, which I have stored elsewhere at the moment but in light of what Ive seen posted here seem rather mild. There were supposedly 5 of these special racing cams made as of 2007, totally custom grind, and there was even a topic on this board somewhere about modifying the oil hole in the cam jounal to properly feed the rocker assembly and solve an oil starvation problem. There is a printout of the post along with my other paperwork. The evidence strongly suggests that this engine was built by a person who did a lot of research and put considerable effort into it. I am familiar with the reputation of this machine shop, they are somewhat of a local legend, and are known for such thoroughness. Only 250 HP max? The guy who ran this engine previously seemed to think the engine ran pretty damn good for a slant 6, and this guy was used to running vehicles with big blocks ( 383 and 440) in them. He said that the low end torque felt like it could just about compare to a stock 383. I bought this engine from a good friend who runs a restoration shop and had the engine built for a customer, who ran it for about 1000 miles in a 73 D100, and reported that it really did make the truck feel like it had a V8 in it, and a strong one at that. I did meet with and hear this from the customer. He took it out of his truck because he decided nothing short of a 440 would do for him. I guess even the best slant 6 can only do so much compared to a big block, even though he did say that the engine changed his whole idea of what an inline 6 cylinder could be...and said it was pretty driveable too. But none of that seems to jibe with what Ive read here. Apparently I have an engine that either makes far less power than everyone seems to think it does or will not run long before it blows up. But I guess I will just have to put it in my car and find out, huh? If 250 hp is the max for a NA, then ok, its the max because I dont have a turbo. But Ive owned a few small block Mopars including a 318 built with 360 heads that made 350 HP in a simular car ( this engine is going in a 72 Swinger, the 318 was is in a '68 Dart 270 2dr hardtop, basically the same car. ) so I guess I will be able to judge whether this thing actually makes more than 250 HP or not. I just got tired of running a V8 like everyone else and wanted something more unique and exotic that may even draw more curious onlookers than my old 318 car did. Even if it isnt quite as fast. My longtime and trustworthy friend said that this engine was going to really suprise me and I would have a car that could give my old '68 a run for its money. Should I gamble and keep the 7 1/4 peanut rear in my car or do I need to upgrade to 8 3/4? |
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| Author: | Oldspowered [ Sun Jul 25, 2010 5:14 pm ] |
| Post subject: | |
Any actual dyno numbers from an actual dyno machine? |
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| Author: | slantzilla [ Sun Jul 25, 2010 5:48 pm ] |
| Post subject: | |
321 at the crank is very possible for a Slant, but it may not be very pleasant to live with on the street. If the 7-1/4 has a Sure Grip unit in it it has a better chance of living than an open one. |
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| Author: | Dart270 [ Mon Jul 26, 2010 5:21 am ] |
| Post subject: | |
I find that most people routinely overinflate HP numbers, especially V8 guys. If you are making 320 HP, then you can go in the 12s in a 3000 lb car. 250 HP will get you low 14s. There are some street cars around with between 250-300 HP, but they are a bit radical. Go ahead and bolt the mill into the car and go to a dragstrip and do some tuning. $3500 will easily get you 250 HP, but 320 HP would be a well economized engine build. Where are you located? Sounds like fun! Lou |
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| Author: | Blackbyrd72 [ Mon Jul 26, 2010 8:11 pm ] |
| Post subject: | |
I am located in Raleigh, N.C. The name of the speed shop that did all of the machining is Boyette's. I made a comment to my friend I bought the engine from today about the 250 hp thing and he stated that this engine had been built to identical specs as an engine run by another racer in a 4 speed Duster that put out 300 hp at the rear wheels on a chassis dyno. He also said that that engine didnt get as much head work as mine did. They have been bowl blended and the ports all matched to the intake and headers. They have oversize stainless steel valves in them. The whole valvetrain including the rocker arms and shafts are custom or aftermarket. I removed the rocker cover and could see that much is true, at least. Thats on top of the custom forged pistons and other nasty little things in the bottom end. The 3500 bucks for the build is actually not retail, as was explained to me today, that was actually the wholesale or jobber cost for everything. Having friends in the right places and times has its advantages. For the average person, it could easily be doubled in price depending on who is doing the work. He says it is streetable and idles smoothly, and that I can drive it to the strip, race it, and drive it home, then drive it to work all week, all month and all year. Take a trip to California, whatever. Thats what he said today when I questioned him about streetability. Call me crazy, but I guess only time will tell. I believe in my friend, have seen enough of his cars over the years to know that hes at the top of his game when it comes to building streetable power, and am confident enough to risk being an idiot if Im wrong. I don't care, I wouldnt be the first or the last person in the world to be wrong about something. I do want to bring my car to events and hope to live up to everything Ive said and run in the 12s or 13s with a naturally aspirated slant 6 and then drive it home. Even if I ran 13s, that would be good enough. |
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| Author: | Dart270 [ Tue Jul 27, 2010 5:38 am ] |
| Post subject: | |
Blackbyrd, I know Boyette's well, and they have done Slant work for me, back when I lived in Chapel Hill. They do great work. Too bad we did not hook up 5 yrs ago... Yes, time and a dragstrip or dyno will tell. Sounds like a lotta work. Just so know, 300 RWHP would be in the neighborhood of the most powerful nat asp Slant ever built. Hope we will see you at some Slant 6 races in the near future! Bristol, TN race is Sept 4 weekend - closest one to you this year. Lou |
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| Author: | slantzilla [ Tue Jul 27, 2010 11:15 am ] |
| Post subject: | |
300 at the wheels and idles smoothly? Just asking, but what does the car run that has 300 RWH and at what weight? Prove me wrong, but I feel a breeze under my shorts.
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| Author: | Aggressive Ted [ Tue Jul 27, 2010 12:00 pm ] |
| Post subject: | |
With that much HP, I would go with the 8 3/4....I went through (3) 7 1/4 rear ends in 5 years just driving on the street and that was with only 160 HP engine....! |
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| Author: | CARS [ Tue Jul 27, 2010 2:31 pm ] |
| Post subject: | |
Can you find an engine dyno to verify the claims? Shouldn't cost too much. Then you will be able to sleep at night
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| Author: | maxracer21 [ Tue Jul 27, 2010 2:36 pm ] |
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If you could find what the head is flowing, you could verify a lot of things. All engines are air pumps. It'll continue to make HP until it stalls. I would be very curious to know the flow numbers. The speed shop should have them on the build sheet. I'd like to know because we are looking for the same HP numbers. Like what was quoted before ..........That's one bad dog if that's for real. It would give us a lot of confidence knowing that it can be done. If You can get the head flow numbers please post them for us, so we know what it takes. best regards MaX |
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| Author: | sergio G [ Tue Jul 27, 2010 2:51 pm ] |
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I have a friend that just had a slant built by a reputable shop.They cut.060 off the head and minor bowl work /port matching etc. The block is 030 over cast pistons.,probably 9/1 comp. and a 468lift cam. They told him this would be 325 hp. So he says now he can outrun Aric Erickson,who has a Jeffrey built engine which may be close to 300hp. I told him he is at least 100 hp short,but he insists he has over 300hp,so i hope he brings it to Redding at the end of the year. Some people are not malicious in their claims ,they just believe what others say or just dont know any better. |
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| Author: | madmax/6 [ Tue Jul 27, 2010 4:23 pm ] |
| Post subject: | |
By all calculations and time slips,my motor is very close to 300 rwp,but a bit under.With the cam and 12.5 compression I have, its a race car motor,not really streetable.My other motor that was streetable was 195 rwhp,but on the edge of beeing real street friendly.I personally dont think a 300 rwhp street friendly slant is possible,unless you consider 110 fuel,1,200 idel friendly.My Opinion.Guzzi Mark |
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| Author: | Shaker223 [ Tue Jul 27, 2010 4:40 pm ] |
| Post subject: | |
Quote: By all calculations and time slips,my motor is very close to 300 rwp,but a bit under.With the cam and 12.5 compression I have, its a race car motor,not really streetable.My other motor that was streetable was 195 rwhp,but on the edge of beeing real street friendly.I personally dont think a 300 rwhp street friendly slant is possible,unless you consider 110 fuel,1,200 idel friendly.My Opinion.Guzzi Mark
Mark,I popped you numbers in too and did not see the same thing. I used 110mph and 2400lbs race weight. Your HP computed from your vehicle ET is 249.54 rear wheel HP and 277.27 flywheel HP. Your HP computed from your vehicle MPH is 230.23 rear wheel HP and 255.81 flywheel HP. Let me know if I have something off. |
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| Author: | madmax/6 [ Tue Jul 27, 2010 6:28 pm ] |
| Post subject: | |
That was in Vegas,wrong tires,going tru the traps at 6,800 on the rev limiter,un tuned fresh motor at altitude.Crunch my 1/8th mile times 7.24 at 92mph at 2435lbs.Curious what you come up with.Mark |
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| Author: | slantzilla [ Tue Jul 27, 2010 6:51 pm ] |
| Post subject: | |
Remember, calculators only tell you how much HP it takes to move a certain weight a certain distance in a certain time. They do not allow for gearing, converter, wind, etc.. Dynos and flow benches are the same way also. Everyone will be different, and even the same one can be different with a different operator. Every one you use will give a slightly different number too. 300 RWH N/A will be a rather uncivilized engine, no matter what the dyno says. The only number that really matters is the ET on the slip anyway. 
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