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I understand from reading some of the older threads that the sprint manifold is basically a stock manifold without the heat riser, so I mostly expected a reduction in performance going from headers to a sprint manifold. Nevertheless, I was willing to do it to quiet the underhood exhaust clatter.

What I didn't expect is that my butt dyno has detected a real improvement in performance over headers. I have a pretty steep hill that I travel frequently when leaving my neighborhood, and I can now take it in 4th gear when I used to have to rev it out in 3rd. Is the sprint really that much better than stock, or is the ignition timing change I made at the same time really what's responsible?
 
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I understand from reading some of the older threads that the sprint manifold is basically a stock manifold without the heat riser, so I mostly expected a reduction in performance going from headers to a sprint manifold. Nevertheless, I was willing to do it to quiet the underhood exhaust clatter.

What I didn't expect is that my butt dyno has detected a real improvement in performance over headers. I have a pretty steep hill that I travel frequently when leaving my neighborhood, and I can now take it in 4th gear when I used to have to rev it out in 3rd. Is the sprint really that much better than stock, or is the ignition timing change I made at the same time really what's responsible?
The Sprint has better torque overall. The header typically makes 2-3 more HP more on a mild engine, but it is at an elevated rpm, not where you drive 90% of the time.

This is even more noticeable with an automatic transmission...a friend of mine put a header on his otherwise stock Opel back in 1983 and we both noticed the reduction of acceleration at lower rpms.

The header can be made better with longer primary tubes and a smaller collector, but sadly it’s difficult to do in an Opel chassis and keep the price reasonable.
 
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Opeler
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The Sprint has better torque overall. The header typically makes 2-3 more HP more on a mild engine, but it is at an elevated rpm, not where you drive 90% of the time.

This is even more noticeable with an automatic transmission...a friend of mine put a header on his otherwise stock Opel back in 1983 and we both noticed the reduction of acceleration at lower rpms.

The header can be made better with longer primary tubes and a smaller collector, but sadly it’s difficult to do in an Opel chassis and keep the price reasonable.
Where does the shorty header fit in for this discussion?
 

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Where does the shorty header fit in for this discussion?
It’s basically just a tubular version of a Sprint manifold, seeing how it bolts up to the stock headpipe and all.

I don’t know if the reversal of the tubing outlet locations matters at all, but the general design mimics the Sprint.
 

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Just Some Dude in Jersey
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I've had oem's, headers, Sprints, and now the stock 2.4 cast iron. I've noticed no difference of any consequence using any of them, except maybe, as Bob said, more high rpm performance with the header. Virtually all improvements or upgrade stuff for our cars are about increasing top end performance, which usually leads to reduced low rpm performance. Nobody makes cool stuff for cars that make your 25mph experience better. There's no market for that. The best reasons to go with Shorties is because they look cool and will bolt up to the stock headpipe. No doubt, they probably give you a boost at high rpms.

:)
 

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Opel Rallier since 1977
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Is the sprint really that much better than stock, or is the ignition timing change I made at the same time really what's responsible?
Did you advance the timing or change the advance curve that made more advance? If so, then that is more likely the reason, but it certainly could be both. You would have to reverse the timing change to separate out the effects.... which you could certainly do.

As for collectors, the first thing I did with one set of headers years ago was to put an 18" collector on it. Made the easily noticeable increase in low RPM torque that it was supposed to do.
 

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Just for comparison’s sake, not saying anything is good/bad/better than anything else. Just a visual comparison.



Stock Sprint on the left, and one of my own fabricated tubular Sprint manifolds on the right.

428517




Opel GT Source Sprint replica, primary tube locations are switched at the outlet flange, otherwise identically functional.
428518



Opel GT Source header
428519


Custom long tube, equal length GT header.

428520
 

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Opel Rallier since 1977
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I have always wondered what may be happening with the fact that the 2-3 ports are immediately joined right outside of the head on the Sprint manifold... if anything. The 1-4 ports have some length before they join. Info? Thoughts?

That is a lot of work on that header....
 

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I have always wondered what may be happening with the fact that the 2-3 ports are immediately joined right outside of the head on the Sprint manifold... if anything. The 1-4 ports have some length before they join. Info? Thoughts?
It’s actually fairly common knowledge, at least in the Scandinavian countries.

First of all, the Sprint is effective up to about 175-180 hp. Which is a pretty damn large range of usefulness....75 hp up to 175 hp or so. Sure, at some point the headpipe’s secondary tubes need to be changed in both length and OD, as does the main pipe diameter. But it’s a flexible combo. Above that power level a proper equal length header starts to pay dividends.

Apparently Jan Carneborn from ENEM in Sweden found that the Sprint manifold could benefit from welding in a divider at #2/3 exhaust ports. As much as 7 hp was found depending on the engine’s state of tune.

In the early 1990’s when I was doing a lot of dyno work on Opels, I found that the center exhaust ports of a 1.9 head flowed more than the outer ports. And as a result, they ran hotter EGT’s. I also found that the Sprint manifold exacerbated this issue and made it run even hotter, whereas individual tube headers did not.

So for any performance builds with a Sprint, I started welding in a divider as well. I saw a few more hp but more importantly, more evenly distributed EGT’s.

My own individual runner tubular Sprint design was designed to alleviate these issues. Not only does it run cooler EGT’s, but the pulse-tuning is improved. Cooler EGT’s on an Opel = longer cylinder head life (cracking valve seats), more power, less fuel used.
 

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Opel Rallier since 1977
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Thanks for sharing that great info Bob. So are the higher 2-3 EGT's just a result of more charge in/out of the 2-3 cylinders with the better exhaust port flow?

How deep into that 2-3 'common port' does a divider need to go to be of benefit? You have gotten me thinking....
 

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Thanks for sharing that great info Bob. So are the higher 2-3 EGT's just a result of more charge in/out of the 2-3 cylinders with the better exhaust port flow?

How deep into that 2-3 'common port' does a divider need to go to be of benefit? You have gotten me thinking....
The higher EGT’s are from over-scavenging. So you need more fuel, but it lights off in the exhaust port, so it gets hotter still.

I've seen some heads that had the exhaust ports ported so much they flowed nearly as much as the intake ports. The trouble is, with a Weber and downdraft anyway, the induction is choked by the carb and intake. The exhaust port flow however, improves when you bolt a manifold or header to it. So it’s not uncommon to have the exhaust system’s overall flow higher than the intake system’s overall flow. This creates higher temps, bad economy, and poor performance. I shoot for 75-78% exhaust flow on the bare ports. If the induction and exhaust systems don’t allow me to maintain something close to that balance, I design a split profile camshaft.

I will give the abbreviated version of an engine I dynoed years ago. It was a 2.0 with 1.5 head and performance cam. 38 DGAS on ported intake, Sprint manifold and 2” exhaust. It made 136 hp and 130 ft lbs of torque. It ran okay water temps, but really hot center EGT’s. I ended up pulling the head, balance-flowed the exhaust ports (more porting on 1 & 4), put in bigger intake valves with more porting there, and reground the cam. Added more intake lift and duration. It then made 155 HP and 159 ft lbs of torque, with smaller main jets and about 200 to 350 degree cooler EGT’s. Balance between all cylinders was massively improved, as previously it was 1375 degrees on the coolest (#1) and 1625 degrees on the hottest (#2).

Anyway, as far as the divider goes, make it as long as possible. You also need to use a real header gasket with the divider intact. The OEM gasket as you know is open at the center ports so it’s a leak point.
 
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Detritus Maximus
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Bob, your custom long tube header is worthy of wall art. I always did like the look of the 'bundle of snakes' under the GT40 engine cover.

How do you think the OGTS Sprint-style Header compares to your version of it as far as the 2/3 EGT's? It would be nice if that was an added benefit of using it. I'm not sure if it has any real performance gain compared to the stock Sprint, but it does look a lot nicer.
I presume the standard configuration of the runners does not contribute to pulse-tuning? My suspicion is some sort of Bob-ness to achieve that?
 

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OK thanks Bob... Got a new project! Cool to know (pun intended) since I am getting ready to put on Webers... the Jetronic is just too doggy at times. This divider ought not to be too hard... just a lot of shaping tedium. I'll figure up a clever way to mount it in the port.... or maybe even a stupid way! :p

Do you have a switchable EGT gauge with 4 sensors? No, I am not going to put 4 EGT probes on my car LOL but am just curious.
 

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OK thanks Bob... Got a new project! Cool to know (pun intended) since I am getting ready to put on Webers... the Jetronic is just too doggy at times. This divider ought not to be too hard... just a lot of shaping tedium. I'll figure up a clever way to mount it in the port.... or maybe even a stupid way! :p
I just tack welded it in about 4 places, but it was a snug fit inside the manifold. I used 3/16” steel plate for the divider and silicon-bronze TIG welds.

Do you have a switchable EGT gauge with 4 sensors? No, I am not going to put 4 EGT probes on my car LOL but am just curious.
The dyno was set up with 4 EGT probes and 4 digital readouts on the screen. The dyno owner recently upgraded the dyno with a bigger water brake (1200 hp now) and upgraded electronics and screen, so it has a greatly expanded capability.

However, I personally do own an Auto Avionics switchable combo EGT/CHT gauge with 4 exhaust pyrometer probes and 4 cylinder head temp rings (they fit under the spark plugs).
 
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