Cure for cracked manifolds?

[Wilko]

A conservative drivetrain calculation back to bhp would put that at 400bhp.

Keith
I believe you have a hub dyno. Do you really believe that a gearbox, drive shafts and tyres loose 37hp as heat and noise? Thats a sh!t load of heat, and even more unbelievable amount of noise. How does the gearbox oil survive at the temperatures needed to dissipate that heat through the gearbox casing.

There are some inertial losses on hub dynos, ie the power taken to accelerate the drive train which is not measured verses the power taken to accelerate the load (which is measured). But if you hold the engine at fixed speed against the brake at points across the power curve, these go away and you're only left with heat and noise as losses.

Gearbox efficiencies increase significantly with load and high ratios, so in top gear with high load, I doubt an automotive gearbox will loose more than a few% of power.



Intakes.
All these intakes will only make noticeably more power if the turbo has some flow capacity left at the intake pressure you are currently running.
Map sensor is pre intake manifold, so decreasing the pressure drop between map sensor and head will lead to higher flow if the pressure at the map can be maintained.
If this pressure can't be maintained, as the turbo is maxed out on flow, then the only power gains are by more even cylinder filling, and the tiny gain that this will give you in timing advance.

On a small port head, if you limit your intake pressure (at map) to 1.6 bar, a gt28rs has some flow capacity left. Do the same on a large port, and it hasn't. In fact it won't hold 1.5 bar past about 6500. A better flowing manifold may give you a few hp on a large port limited to 1.6bar map, but the turbos maxed out flow wise already, so not much.

Run a 2871 at 1.7bar max, and the same is true. So in conclusion, you can get the same flow gains by upping pressure, and will only loose out a little due to less even cylinder filling and slightly lower charge density.

The apr sem manifold dyno you post is interesting, as get 10whp different on a dynojet by running 5th instead of 4th (02m transmission) ad the dynojet just won't give enough load to spool my turbo in 4th, so I'm pretty sure I could do the same test in reverse and give proof that the SEM manifold destroys the APR one.

I don't believe that either destroys the other, as they are both well designed and should both be nice additions to any high power 1.8T. I bought an RMR which gave me some timing advance gains and had a measurable drop in map pressure at max turbo flow. I'd say buy the one which looks the prettiest, as it's the main difference you'll find between these manifolds. Personally I like the short runner rmr as it should be good for the 5000-8200rpm power band the 3076 will give.



Anyway. Back to the original topic. Cracked jabba manis. Yes they do crack. Mines got over 40k on it, and is cracked to hell, but the cracks close up as soon as it warms up. Had 7 different turbos on it in that time. The mani survives, the turbos don't. Don't worry about it unless they blow a lot when hot.

 

[DarkAge]

all manifolds have limitations based on the materials used, heat, and welding strength & penetration. I've typically found that custom made manifolds in 301 stainless steel welded with TIG and wrapped lasts well with all the heating/cool down compared to mainstream products. I don't have much knowledge about the products mentioned in this topic. Just my .2 cents

 

[Don R]

Our clients are seeing 40+ whp with our intake mani as supplied with our throttle body bolted and at a minimum port matched onto a 180 hp 1.8T with our Stage 3+ Turbo System and production ecu upgrade.

Here is a thread from vwvortex that relays the results of the first independant testing. This guy port matched his head on the intake side only with a dremel tool in his driveway.

http://forums.vwvortex.com/zerothread?id=2722000

The thread is old so the pics are gone but you can read about other posters applauding his results starting on page 6.

Here's a new thread by a client in Denmark.

http://forums.vwvortex.com/zeropost?cmd=tshow&id=4533826
40+ whp with our intake mani, w/m and new spark plugs:

And here you go! A direct comparison of the APR intake mani vs. the SEM mani that was swapped on the dyno and retested on a 3076R and Unitronic software:

In the States, this information would be considered to "destroy" the competition's offering quite handily.

Keith, I respect APR and although the APR did provide gains I wouldn't say it will destroy the SEM. I tested back-to-back on my own GT3076R from stock, APR, and SEM all within a span of 20 min apar from eachother. Everything the same except for the stock TB on Stock intake, RS4 TB on APR and 80mm TB on SEM. SEM clearly makes about 15whp more up top in this case.

Another point I'd like to point out is the information between the dyno you posted above vs this dyno that was supposedly made on the same setup shows completely different power curves?...Little weird huh? It also shows the SEM power curve converging with APR's and just about to pass it up top...leaves me confused.

Moving on, here's a dyno plot between SEM vs 007 taken from this thread: http://forums.vwvortex.com/zerothread?id=4315542

 

[JNL]

Just thought I'd add a little insight into dyno figures of back to back comparisons between intake manifolds.

Any such test is always going to be limited as it is assuming everything else is a 100% correct and matched along the whole chain of events of intake through to exhaust.

For example you take a car with setup X. This car makes good power has a cast log manifold with with a .63 backhousing on say a 3071R.

It makes a dyno run with a standard manifold and for arguments sake makes 400WHP.

You now bolt on manifold A redo the dyno test and it makes 420WHP

Finally you bolt on manifold B amd once again run it up on the dyno this time making only 395WHP

So which manifold is now best? Std A or B? Most would say A but the answer is actually inconclusive as there is not enough information.

So lets add some more info to the equation Manifold A flows 10% more than std and manifold B flows 20% more than standard.

Which one is better now? Flow calculations and measurements say its B but that mani makes the least amount of power?

So what this tell us? It tells us that there is another restriction in the equation. It's all good and well shoving more air in but if you can't get it out you get raised EGT's and you have to back of ignition timing which can loose as much as 8-10WHP per degree of timing.

So now you fit a better flowing tubular manifold and a larger wastegate to bleed of excess exhaust gasses in the higher rpm range where the .63 housing is too small for the application.

This time round the dyno results are as follows

Std 400WHP
Manifold A 420WHP
Manifold B 430WHP

So which is the best manifold now? Most would say B. However the answer is all of them. One has to look at the application and the complete setup before deciding on what manifold to use. After which they will only reap the benefit if tuned correctly. Unfortunately too many tuners still just tweak generic maps rather than custom mapping on aftermarket management. Which results in conflicting hp results when swapping components about.

You see for average applications Manifold A has the capability of potentially making the most gains with the least amount of changes. However if going balls out and matching the setup correctly with a correctly adjusted map manifold B would win hands down each time. In the same token if it was a smaller turbo application a standard manifold would be a much nicer driving experience. It may not yield the same pub figures but be a much nicer drive.

Finally something to keep in mind On a standard AGU largeport manifold with 8 440cc injectors on a standard largeport head with ATP cast manifold and a GT30 turbo with an .82 backhousing as far back as 2002-3 UK tuners made 456hp at the flywheel.

Likewise on a modified smallport manifold (larger plenumb) and a ported small port head (small port size kept) atp cast mani with a GT3071R and .82 housing 500+hp at the flywheel has been made.

JP