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my 302
my 302 / 354 makes it's hp / tq before 5500. I'm making 350 ft lbs of torque at 2500 rpms. I don't have any trouble hanging with my big block buddies and their 600 plus hp motors.
I run 3:55 gears and a TKO 600. Cruise at 1200 1500 rpms. 2000 rpms gets me 70 mph. You need to consider your cruise speed. With the wrong cam or rear gears and you will have "trailer hitch jerk". I think a street car / motor should make it's power from 1500 to 4500 rpms. That is the range we do most of our driving. Dwight |
The only drawback to the rev kits for the motors that they are available for--is that you can't change cams quickly between qualifying periods or heat races/rounds---anything that you can do to eliminate some of the force from the valve tip/keeper/retainer is vital and keeping the roller on the base circle of the cam is minor compared to being able to eliminate that shear force up top--
of course , I probably only have 8 to 10 bushels of used valve springs |
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I routinely shift at 6,500 to 7,000 rpm. The engine is an essentially stock 289 Hi-Po K code. It is a flat tappet engine, with a stock Hi-Po cam. There is no grumpiness at any rpm, idles fine at 900 and is smooth to 7,000+ rpm. In a nine year time span I've got over 45,000 miles on the engine. Seems very durable to me. With good lubrication, meaning an oil with plenty of zinc, there are no issues with cam or lifter wear. Been using Mobil 1 15w-50 the entire 9 years. Z. |
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Brent - what is different here that enables this engine to do what Z describes, and do what I want an engine to do? The way I see it, if I want an engine that revs (but behaves at low revs as well) I need to start with a smallish engine, use good (light, balanced) gear for the rotating bits, and not go 'I need more power/more cubes'. But I'm definitely not the expert here, so tell me where I'm going wrong in my thinking. Cheers! Glen |
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Glen |
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Seriously though, a stock 289 K code engine that has been balanced properly is a great little engine. With some improvements to the breathing, like a good set of AFR heads, or a vintage Paxton (as I have), then 350+ HP can be expected. Or you can stroke it to 331 or so if you like strokers. However I like the way the short stoke (289) engine revs quickly, so stroking is out for me. Z. |
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A stock K code 289 was rated for peak horsepower at 6000 rpm. Why shift at 7000? As I mentioned earlier, an engine with a lower peak will have better manners down low and more power available down low. All of this makes a huge difference. BTW Z, I was just offering that question up for thought in general, I wasn't directing it at you. |
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4th...153mph at 7000rpm 3rd...112 at 7200 2nd...89 at 7200 1st... 67 at 7200 Why not shift at 7000 if the little rocket will pull those revs in top gear! OK, admittedly this was a 'Press' car, and it's paper figures would not match its actual figures, but this is 1962, remember, and these figures are sensational! Can we not have this rev-ability and apparent mild enough temperament now? Cheers! Glen |
You answered your own question. The engine that was shifted at 7200 wasn't the same engine that peaked at 5800. If it was, then I say shame on the drivers as they apparently had no clue on how to drive. Did they mention how the car ran at 1200 rpm while driving downtown? Or how well it took off on a hill with a 3.07 rearend?
You seem to be pretty adamant about what you want, so I say build it however makes you happy. However, remember that you posted to get opinions. I have given you opinions plus a great amount of real world data. |
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I have a 302 stroked to 331. Scat forged crank, JE pistons, Crower Sportsman rods, AFR 185 heads running Webers. Solid lifter Comp 282S cam
236/236 @.050 with a .512 lift. Dyno at rear wheels was 340 hp. I use a richmond 5 speed with a 3.07 rear. It tachs 2800 at 70 mph. |
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It's not EXACTLY stock, but essentially stock. I should have posted the differences. It does breathe a bit better, and I suppose that is why it is still pulling strong to 7000+ rpm. I had it dynoed years ago, but don't recall the exact peak numbers. I do remember that the operator was wanting me to OK a higher testing rpm than the 6,800 I had authorized, as the engine had not dropped off in power yet at that level. I have slightly bigger valves, a mild head porting job, Crane Cams gold series aluminum roller rocker arms, a 2.5" MagnaFlo stainless steel exhaust system, a msd digital 6 ignition, a high volume Melling oil pump w/ a Melling oil pump shaft, and a vintage Paxton supercharger. The intake & headers are the Shelby supplied items (Cobra lettered hi-rise intake & tri-y headers). The bottom end is stock. Z. |
Thanks for the info Z.
The supercharger is certainly giving you a "boost" (pun intended)....quite a bit more torque all along the curve. Something that a naturally aspirated 6500-7000 rpm 289/302 wouldn't have. |
yes, it's a lot of fun. but can't help wishing I could shed 800 lbs. of vehicle weight and be able to zoom along like you lucky Cobra owners.
by the way, the dyno experience was done without the supercharger, so this particular engine has been rev-happy to 7000 rpm for quite a while. Z. |
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Example-I switched from a 3.77 to 3.31 and gained 11MPH at 6200RPM with the same tire. I have a 33 pound wheel so there was no penalty to decrease leverage---also about 400 pounds of torque from about 2500 to the 550 pound peak. You need to increase leverage with what your planning. As Brent said earlier, you've got to compromise some areas to get benefits in other areas. |
There's a couple issues you guys are not considering---
#1----why shift at a higher rpm than peak hp/tq numbers???? remember that the older trans (4 speeds) had wider gear ratios and with the smaller engines we had to turn them WAY over rev so as not to fall out the bottom of the hp/tq curve on upshifts AND when down shifting, the engine r's would go pretty high---- #2 flywheel weight----with a small engine a high rpm leave with a heavy wheel allowed us to get going in a drag race AND we could get some extra umpt as we upshifted except for road /circle racing , the heavy flywheel put an unnecessary demand on some pretty inadquete brake systems Of course back then we didn't have a wallet full of dyno numbers to shift our butt weight to assist with clutch or brake pedal effort--- In all my years of racing back then, I never had an engine that had been on an dyno, so we did what made it faster by moving shift points or playing with flywheel weights |
My friend back in S.A. had a pretty stock 289 ,with a 5 speed , I don,t remember exact specifics, but I remember him driving the sh*t into that car everyday. He never complained but sure had a lot of pleasure from that little motor. Ps. He never got left behind either.:JEKYLHYDE
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Some of you guys have built more engines than I’ve had hot dinners and I appreciate your advice greatly, thanks.
Compromise is usually necessary, so you look at what’s important and what’s not. I want a Toploader so OK maybe I need to shorten my final drive ratio a little to help driveability. But the engine….I don’t want a stroker, I want something closer to the original. 289s are too hard to find, so it’s a 302. That 260 engine in the first Cobra, the one that did the rounds of the car shows and was repainted many times to make it appear that there were more cars in circulation ….that was the car that was also road-tested by an long line of motoring journos. There’s no doubt that motor wasn’t a standard 260; it was modified to make the Cobra look extra special in the road reports. But…I don’t recall reading in any magazine reprints that it was a b*gger to drive at low revs. Surely somebody would have mentioned low rev grumpiness if it was a problem? All reports mention 7000 rpm, 0-60 in 4.2sec and 150 top end. I read those figures and I think, that’s what I want (assuming it's driveable!). So....if that is not achievable, then please post "That is not achievable. Compromise, and move on!" Cheers! Glen |
With a 3.54 or 3.70 rearend gear, I would compromise on the engine specs and let it pull a little higher. However, with the 3.07 gear, I'd aim for a lower powerband.
Building an engine to pull to 7000 is absolutely pointless if you spend most of your time at 1500-2000 rpm. You may think that it would be more fun and enjoyable to watch the needle peg on the tach, but an engine with more torque and a more usable powerband will feel much stronger to you. As for the 331/347, it's going to be much more cost effective for you to go this route and there's no use in passing up on cubic inches. You can't tell what size an engine is by looking at it, and we're all driving replicas anyway. Keep in mind that a nice street engine will make about 1.4hp/ci. If you add almost 50 cubic inches to that 302 and increase the stroke by almost one half inch, you're going to gain about 65hp and probably almost as much torque. There's no reason to pass up on that and it will help offset the lack of bottom end that the 289/302's have, especially when you're trying to pull to higher rpms. By the time you pay a machinist to grind a crankshaft, recondition rods and fit them with good fasteners, you're more than halfway to a brand new stroker kit. So.....compromise and move on. :D |
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It was very common in the day for ringer motors and popcorn times to help new marketing-like the 389 GTO, elephant Hemis, and a million GM projects like the Z-28 and 396, 427, 454 cars. Consider building a brand-new, 49 year-old project or a modern project which will truly add to your enjoyment of your work. There's really no comparison. |
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