Longtubes+Blower=?

[Skyman]

As long as Im install the blower, should I go with long tube headers too? Is it worth it, for the extra cash?

Skyler

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-1989 Saleen Mustang #406-
TFS Heads, Edelbrock intake, E-303, 3.73's, 1 5/8 shorty headers, Offroad-Hpipe, 2chamber flows, 36psi FPR, playing with timing still, 70mm tb, 73mm maf, 24lb injectors, K/N, March Crank pulley, MSD6a, 9mm wires and FMS Aluminum driveshaft.
Best ET 13.2@106mph Needs tuning...

Yup,I would go for it.You'll get more torque and HP yet going with the long tubes and they will allow the motor to breathe easier.

Stay with a 1 5/8 long tube header as the 1 3/4 headers are for race/high RPM motors.Myself I have the Mac 1 5/8 long tube headers and have had no problems.



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Paxton Blown 87GT

To be honest Sky,your short tube headers that you already have will work just fine,it's just the idea of gaining more torque and HP yet that the longtubes give a person that makes it more attractive

[evilstang]

Dont waste the cash. had motors on dynos alot,long tubes are for natural asperation.

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IF ITS NOT BLOWN IT SUCKS

Long tubes are for natural aspirated motors

Hmmm,then tell me why people with a blown combinations with shorty headers have faster ET's when they switch from short tubes to long tubes? Blown motors like high-flow exhaust set-ups..

[evilstang]

Long tubes are equal length shortys are not very finicky motors like equal back pressure being a relitively stock motor it wont matter.

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IF ITS NOT BLOWN IT SUCKS

The fact is long tube headers develop more low-end torque and power all across the rpm band in a blown application due to their better scavenging design.
This is most important in a centrifical blower application as they start producing boost at/around 3000rpm and climb to peak boost around 5500-6000 in most street applications.

[LX XLR8R]

my buddy ran 14# of boost and long tubes..here is his mods and his times..you tell me what you think

1990 GT:bone stock bottom(high pressure oil pump) milled and ported '69 351 heads(10.5:1 compression),upgraded "b" trim vortech(14# of boost), gt-40 intake w/ 3/8" plen spacer, 24# inj with Pro m 77, b-303, 4.30's with auburn diff, 1 3/4" long tubes, 65mm tb, 255 fuel pump..

his times were 10.2@???(i dont remeber)

only suspenion was motorsport HD uppers and 50/50s out back..this run was on draglights all around(skinny in front..10.5" slick out back)

so big long tubes and blowers do work well 2gether

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1987 black notch(ex 4 banger)
DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one..

[This message has been edited by LX XLR8R (edited 01-12-2001).]

[Skyman]

Ive seen a few people running high compression with boost, and it seems to work out ok on lower boost apps. Hmm... What If I milled my heads, as I'm only going to run 9psi.

Mustangguy- Whats all the stats on your car?

Skyler

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-1989 Saleen Mustang #406-
TFS Heads, Edelbrock intake, E-303, 3.73's, 1 5/8 shortys, Offroad-H, 2chamber flows, 36psi FPR, 15degrees timing, 70mm tb, 73mm maf, 24lb inj, Crank pulley, MSD6A, Alum driveshaft.

On its way: Paxton Sn-89 with dyno tuning and long tubes.

Just added: B&M Ripper, Weldin Subframes, & Turn downs!
13.2@106mph

[buddha]

I had the shorties, went to the long tubes, and didnt see any gain at the track. I'm sure I would have seen the difference on a dyno, but it would be marginal. So you decide if it's worth the extra cash.

[NO SLO PK]

Originally posted by Skyman:
Ive seen a few people running high compression with boost, and it seems to work out ok on lower boost apps. Hmm... What If I milled my heads, as I'm only going to run 9psi.

Sky, high comp. and boost = NFG for a street car. I've got 10.5 compression with 11 lbs., and it always wants to detonate, even with a 3 row intercooler. I blew 2 head gaskets, and only with this setup.

Next weekend I'm dusting off my old Edelbrock 2.02 heads to bring the compression down to 9.3 which should be more streetable.

My personal experience and those of my friends and shop owners is that the long tubes are worth the effort and give good gains over the shorties.

With the induction improved via the blower, the exhaust becomes more of a bottleneck. I think you'd be happy with the longtubes.



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'91 LX
Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.

You'd have to buy a new h-pipe too, save your money. You already have a performance exhaust. I've never had long tubes before but I can't see where it will make that much difference and definitely not $600 worth. The blower is forcing air through the engine already, scavaging is related to a NA motor.

[MiracleMax]

any engine can benefit from a properly designed header. Even a super-charged engine. Until the intake valve opens there is no positive displacement of the exhaust gases. In the case of a header. It needs to be of sufficient cross-section to handle the additional volume of exhaust gas. Say for sh1ts and giggles the engine has a peak VE of 125% on the super-charger and its a 302. Then the engine is equivalent to a 377 cid motor in the volume of gas that needs to be expelled. So lets do a little math here.

First of the SC engine is putting out the same volume of spent exhaust gas as a 377 cid engine, so divide that by 8 = 47.18 cubes a cylinder (VE based)

This is the formula for determining primary pipe size at peak torque (we'll use 3000 rpm)

(CID/8) x Peak Torque RPM/88,200/17724538509 x 2 + the wall thickness of the primary pipe material (x 2) = 1.850 (closest pipe would be an 1-7/8 ). thats at peak torque. Figure peak power is about 1500 rpm higher and plug this in.

(CIDx1900) / (RPM x PPA^2) or

(377 x 1900) / (4500 x 3.7) = 43.02 inches

Okay so on this supercharged 302 with a VE of 125% the engine needs a 1-7/8 x 43 inch primary tube header with a 3-1/2 x 21 inch collector. (using a peak torqe at 3000 rpm and a peak power at 4500 rpm).

This is all just pluging in some numbers and getting in the ballpark. there are more exacting formulas using valve timing events to accurately place the primary pipe length. but it illistruates the point that even a supercharged engine can benefit from a long tube header. IMO before the intake valve opens and the cylinder is blown down via positive displacement of the super-charger.

What are you saying here?
I don't understand why you are bringing in formulas and assuming(grasping) at numbers, that defeats the scientific approach. The fact of the matter is that the engine is pressurized and gas will be forced out. A specific header tuned for a specific engine will definitely make more hp or move the curve somewhat, but we aren't talking nascar here. We aren't spending $1m and maxing everything to the limit for .001/sec. I'm not trying to flame, I'm just saying that $600 could be much better spent elsewhere.

It just hit me Sky. Take that money and get a dyno tune/custom chip burnt for your ride. You would see much more hp and that would be money much better spent..

[MiracleMax]

Grrrrrrr.... Just kidding

Well really to get a properly tuned header you need to know the VE, peak power, and peak torque. and to nail it down the timing events for the cam. Generally most headers just produce a reduction in pumping losses. But a tuned header could produce 40 to 60 ft/lbs of torque over a non tuned header (or more!). Thats not to shabby. If the header produced a 50 ft/lbs increase in torque on the above engine at 3000 rpm that would be worth 28 hp at 3000 rpm. Say you could do the same at 5000 rpm thats 48 hp (torque x rpm/5252). Granted a set of custom headers aren't exactly the best value per dollar in the world of horsepower but neither is a Victor JR intake on a bone stock engine. However between two identical engines except for exhaust the engine featuring a tuned exhaust system will have an advantage.

More specifically the above math (given correct inputs) could point somebody in the right direction when they are trying to select a header. Making HP is not just waving a wand over a hat and saying presto. It's really a matter of sitting down taking a look at what your trying to make and doing a little math to see what parts will work out for you. As another (and cheaper example) A Victor 5.0 intake has 11.5 inches of runner length. Which is tuned to take advantage of a 3rd pulse pressure wave at about 8000-8500 rpm. Add a 2-1/4" spacer in there and you've lowered the resonant tuning to 7000 rpm ( acutally you measure from the valve but it illustrates the point). How much is a spacer (especially if you make one yourself). Or this one for figuring out how much cylinder head flow is need to get a certain amount of hp (hp=.2575 x CFM x # of cylinders) thats at 28" of water, but could save you some bucks. Juggle things a bit and you could determine how much cylinder head flow you would need to make certain amount of power ( CFM=HP / 8 / .2575). For 500 hp you need 242 cfm of intake flow. Okay so now you know how much airflow is needed to make 500 hp. Armed with the knowledge you can select a cylinder head and save some money on porting. Or armed with the same knowledge and you need to have a set of heads ported, you have an idea of what needs to be done. That way you don't sell yourself a bunch of stuff that you don't need or get suckered into a bill of crap just because somebody says yeah I can get 400 cfm out of those heads and it'll make 500 hp.

True not everybody is building a top level competitive engine, but given some theory (and all this stuff is workable on a regular calc or the scientific calc shipped with windows)you can get a bit more out of your engine compared to the next guy.

Superchargers and Nitrous make for dumbed down HP (no flaming here) but they can still benefit (especially when the bottle runs dry ) from a healthy dose of math.

[NO SLO PK]

Originally posted by rbatson:
The fact of the matter is that the engine is pressurized and gas will be forced out.

Actually, the blower doesn't help the exhaust side at all. By adding a blower, you've increased the capacity of the induction side, but you've done zilch to increase exhaust flow capacity. As a result, the exhaust is likely to become the bottleneck.

Hey Miracle M, I followed your forumulas -- I haven't really analyzed them but I definitely agree in concept.



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'91 LX
Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.

Sky:

Sent you a PM

[Skyman]

Well I have been reading on Corral.net and Ive seen a LOT of bad news about the Paxton SN serious blowers. They seem to be very un-reliable and go after about 10k miles or so. Putting an oil cooler on it seems to yeild to more life, and not over spinning it. So that means only a lowly 5psi of boost. This isnt even worth the damn money. Anyone wanna buy a nice Paxton SN-89 setup? I'll throw in a boost pulley of your choice.

Skyler

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-1989 Saleen Mustang #406-
TFS Heads, Edelbrock intake, E-303, 3.73's, 1 5/8 shortys, Offroad-H, 2chamber flows, 36psi FPR, 15degrees timing, 70mm tb, 73mm maf, 24lb inj, Crank pulley, MSD6A, Alum driveshaft.

On its way: Paxton Sn-89 with dyno tuning and long tubes.

Just added: B&M Ripper, Weldin Subframes, & Turn downs!
13.2@106mph

[NO SLO PK]

Hey Sky, I didn't want to tell you it that it was kind of a POS (no offense, remember I owned one). Like you said, sell that bad boy and get a Vortech or ATI.

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'91 LX
Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.