I'm building a 37 Ford coupe with a 302 and C-4. Dad had the car mocked up with an exhaust system using stock exhaust manifolds and a 302. The 302 was just a worn out mock up engine and I've pulled it - had it bored .030, got an Edelbrock intake, holley 600, flow-tech heads, 331 stroker kit, and a mild roller cam since there seem to be soooo many issues with flat tappets these days. The car has a dropped I-beam with stock wishbone and a Saginaw 800 power steering box. I've had several people tell me I would be choking my engine with the cast iron manifolds but with the wishbone and the Saginaw 800 there is just no room for headers. Are the Scott Drake Hi-Po exhaust manifolds really any better than the 302 manifolds I already have ?
I don’t know about the Drake manifolds, but on the street my opinion is you will probably never see the rpm’s where headers make a difference.
Got agree with KevKo for a car that you are primarily going to drive on the street the stock manifolds will only cost u a little horsepower. If you have access to it the guys on Engine Masters have done a comparison on one of their episodes. If you want to improve the stock manifolds flow you could have them Extrude Honed. Also have you tried a pair of Ford Fox Body headers they might be a low cost performance option?
^^^This I was the FoMoCo dyno engineer on the Mustang 5.0 GT program. The shortie, stainless steel factory headers lost only about 5 - 10 HP compared to long tube headers, when running a full, dual exhaust system with a crossover pipe.
Why is it that most of us don't give a second thought to totally building a project on our own but will not build our own header system to fit what we need? A simple Tri-Y system is for sure first grade in the exhaust world, and they actually work pretty well as long as you step pipe as you go. Much better than stock manifolds.
The HiPo manifolds are better than 'most' 302 manifolds and nearly as good as shorty headers. Two advantages are they're less likely to leak or crack like headers, as well as being a bit quieter. More compact too, so may be an easier install.
The amount of room available would dictate making headers that almost look like the same shape as stock manifolds, like one long runner from the front cylinder with the other 3 joining in -- probably no better than stock manifold but a lot more work and potential for leakage -- so I sort of discarded the idea of making headers on this project. Dad had originally built stainless headers for the previous engine -- a Boss 351C going into the fender wells and the mufflers were hung under the running boards, but that was when the car had the original early Ford steering box -now the Saginaw 800 (and hoses) take up space that the headers would need.
If the Hi-Po exhaust manifolds are better than "most 302" manifolds then they are probably better than the 72 302 2 barrel exhaust manifolds I already have. Thanks
Lotsa my "M-word" buddys swear my the HiPo manis. They don't sound as cool (IMHO) long tubes but........they don't leak like'm either ! 6sally6
On a performance build like that I wouldn’t even consider stock 302 manifolds. The hipo manifolds if they fit without interference would be great. First choice for me would be a header kit and build my own tri-y setup. Good luck.
I have a couple scarce 289 4 v not HiPo from a Comet with 4 speed . I think one will fix you up fat .
https://www.ebay.com/itm/166503668364?fits=Submodel:GT|Engine+-+Liter_Display:5.0L|Model:Mustang&hash=item26c4645a8c:g:7z8AAOSwqtBlfd0c&amdata=enc:AQAIAAAA0NUxe0el6Ok7q29JCGVLMQWg2Bp752RU0fGjDvOdGL41lTHBZs7Ina8zRODHHvKYJWi34HQHrM96Ps9MjsAvuSvL5WBjYpYmKtWOU/dvPpGTJ5DrNezUp0e7ipgGpdiyUJzMBiYaLl+2LV9WU4B383jNtmydAmJ34C1oE31wo5c3hRFbVCtk/bZJfMsYbafVTfQip/XuapO+FgTOk/waD1/3wZQ13fHI83x4JMmmhNobc64tVvTYlT0mAGH1YB5jgX/Y5FDLtrA3u8qPjPf28AI=|tkp:Bk9SR8S63dWPYw $8o - or less - and down the road you go or this: https://www.ebay.com/itm/1658815248...c5HUmnfsLj%2FA%3D%3D|ampid:PL_CLK|clp:4429486
Yeah, when Freiberger had an engine on the dyno with some headers and started smashing the tubes, it showed that the flow didn't affect power at normal street operating RPM. https://www.motortrend.com/news/eng...es-headers-for-horsepowerso-you-dont-have-to/ Unless you are building a hoodless, fenderless 37 that shows the exhaust, I don't see why you would bother. If you dig the fab work, you could make some nice heat shields for the floor and starter.
There are a few other choices that may be worth looking at as I don't know your particular fitment issues. '69-72 full-size Ford car 351W manifolds are configured a bit differently compared to the HiPos but offer a bit better breathing compared to the standard 302 pieces. Those would probably be hard to find these days. A more common similar choice is the late '70s to late '90s 351W truck manifolds. These are heavy-duty, a downside is the heavy reinforcing ribs cast-in making them both heavier and bulkier. But the ribs can be ground off. All of these (including the HiPos) will benefit from port-matching the manifolds to the heads. Be careful around the bolt holes, it's thin there.
Supposedly, the mid to late seventies 302 Maverick manifolds flow better than earlier manifolds, and the outlet is more suitable for hot rod applications. I can’t personally verify that, though
The engine is a 331 stroker, half decent heads, roller cam so it should make 350 hp with a good flowing exhaust from the heads to mufflers. With restrictive manifolds I could losing at least 15-20 hp with small port iron manifolds. Not the way go for a performance build.
I used Explorer manifolds to clear my steering box. They come in a cast version or a tube header style. They carry the front two tubes up and back, then drop at the third port, with the rear port coming forward. Maybe not the best flow, but in my case it was use them or build a set of custom headers, which I didn’t feel comfortable doing. I’m not the best welder on thin tubing, so they probably would have ended up looking like crap.
Dyno testing on those Explorer manifolds showed they were bad, even worse than the cast exhaust manifolds, but if they solve a real estate problem, like they did on the Explorer, go for it.
I've got stock (std non performance) manifolds on my 37 Ford Ute with a 302 SBF. Stock wishbone and X- member also. Agree it's a tight fit for any exhaust and with my close to stock 302 it's a tradeoff that works.
Around here you can buy stock 5.0 headers for $50 a pair. They flow pretty well and there are two styles. One style is a simple 4:1 and the other is 2:2:1 both stainless and long lasting.
The HY-PO manifolds work fine. They are not hard to find. as for street RPM I wing my motors pretty tight. That is what they are built for. I got to believe that I am not the only one who drives one. I could be wrong.
I pm'd the OP Monday [Dec 18] about some MAC'S shorty headers I have, needing his clearance dimensions. No response.
They fit like they were made for the car. I’ve seen those reports, but it doesn’t matter much on my car, it’s just a stock 5.0 roller cam motor. I figure it and an Explorer probably weigh about the same, so the performance would be about the same. If I had it all to do over, I’d raised the motor and transmission about 2” and used the Mustang shorties I had planned on to start with.
Now those are a bunch of snakes. I am afraid I am going to have to build a set of those for a Cleveland.
As several have already correctly stated, with a full exhaust, all the way to the rear bumper of a street car, the small tube OEM manifolds will be just fine. OTOH, custom long tube headers with straight through mufflers bolted on the collectors and turndowns as short as possible, that's a street exhaust for some. (Reminds me of how that setup cost a guy a same day plane ticket home and almost a divorce. He put the race setup on his just-completed 496" BBC in his '55 Chev and took his wife on a 300-mile run to Cruisin' the Coast. The noise was a big-time-deal-breaker for her.) jack vines
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