Relocated exhaust port T1 Style.

Joe vw · Post by **Joe vw** » Fri Oct 22, 2004 5:54 pm

Hey Jake have you ever tried it? Not on your new heads but welding on stock heads. I did a search but came up empty. Any pictures? Anyone else? HAM? I know it wouldn't be easy, but someware someone must have done it.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Sat Oct 23, 2004 6:18 am

WOW, Yes you could do it, but since thestock head is fully finned in that area and the casting has no reinforcement behind that area of the chamber it would be risky as well as VERY labor intensive!

tuna · Post by **tuna** » Sat Oct 23, 2004 10:26 am

Years ago, there was an engine builder in the high desert area of SoCal that did this particular modification. I don't remember the details, but the one I saw was in a sand rail. It was very labor intensive.

Tuna

HAM Inc · Post by **HAM Inc** » Sat Oct 23, 2004 2:37 pm

Contrary to popular belief a modified typeIV exhaust port is capable of keeping up with the intake port. For any combo other than fixed speed (such as stationary) the best performance is derived with heads in which the exhaust flows 75-80% of the intake.

No need to convert to the TypeI style exhaust port as the intakes, while impressive, can't be opened enough to take advantage of the extra exhaust flow.

Plastermaster · Post by **Plastermaster** » Sat Oct 23, 2004 3:05 pm

Does this mean that the bad rap of the infamous T4 exhaust port position really not true? Is the only advantage of the T1 exhaust port more header options? If it just a matter of head work, both T1 and T4 need work to make power.

Ron

Ephry73 · Post by **Ephry73** » Sat Oct 23, 2004 7:06 pm

Oh no! Hide from Dan! lol

Ephry

Racer Chris · Post by **Racer Chris** » Sun Oct 24, 2004 5:13 am

Plastermaster wrote:Is the only advantage of the T1 exhaust port more header options?

Why would you pay $$$$$$$$$$$ for modified ports just so you could get a header for $?

Plastermaster · Post by **Plastermaster** » Sun Oct 24, 2004 6:27 am

Racer Chris wrote:
Plastermaster wrote:Is the only advantage of the T1 exhaust port more header options?
Why would you pay $$$$$$$$$$$ for modified ports just so you could get a header for $?

That was my next question.

HAM Inc · Post by **HAM Inc** » Sun Oct 24, 2004 10:51 am

Aside from the inconvienence associated with the typIV exhaust position the position doesn't really put the port at a disadvantage. I've proved this on the flow bench. Ofcourse in theory it is an advantage for the exhaust to exit up to take advantage of thermal energy (heat wants to rise.)

As far as typical pushrod designs go the typeI exhaust port is a bit of an anomoly. Most pushrod exhaust ports are not all that unlike the TypeIV, that is they are short and make pretty sharp turns directly beneath the valve.

The typeIV ex.port's bad rep. is well deserved as far as o.e. specs are concerned. The exception is the 2.0 914 head. In that case the ex. port is larger in volume and the turn is about 6mm deeper. This port can be reproduced on any of the oval port heads.

Experimentation with sq.port heads has produced a port that outperforms the 75% rule of thumb to such an extent that further work with the intake
port is required to take full advantage of it.

The TypeI intake port needs work to keep up with the superior exhaust port. Both heads have shortcomings that can be overcome with modifications. The O.E. typeIV heads are capable of producing impressive torque #'s on engines up to 2500cc. This is beyond the ability of the o.e. typeI head because of the intake limitations. ( Not trying to start anything here. I love both engines, and I don't hold it against the typeI head that it doesn't have what it takes to supply an engine 900cc's larger than it was designed for).

I'm with Chris on the puzzle of folks spending big bucks on their engines, including ex. port work, and bolting crappy headers on. THe header should be a starting point, not an after thought. It is tough to find another single bolt on item that can make such a huge difference in performance. Enlightened engine builders approach the cam, rod/stroke ratio, head design, induction and exhaust systems as one package. Change one element and it effects the choices made with other components. Don't believe it? Look at the differences just in cam selection in race classes requiring stock exhaust vs. headers.

Plastermaster · Post by **Plastermaster** » Sun Oct 24, 2004 11:36 am

Len, this is very important here. (That is a more sophisticated way of saying "This here is very important"

) I have always liked the T4 head, based on alot I have gathered on these forums. I have seen the torque advantages, and the shortcomings in flow numbers compensated for, first with cam choices and more recently with your work on the heads themselves. On top of that compared to a T1 you can stick big ass engines between them. Still, fairly recently I have seen posted that for all out power, the T1 is still the best choice. Is there a piece of the puzzle I am missing?

Ron

A_67vdub · Post by **A_67vdub** » Sun Oct 24, 2004 12:27 pm

Plastermaster wrote:Still, fairly recently I have seen posted that for all out power, the T1 is still the best choice. Is there a piece of the puzzle I am missing?

Ron

My guess would be power adders (turbo & NOS) and non-oe heads. I don't know how the type 1 would do against a type 4 NA with worked oe heads.

Steve

HAM Inc · Post by **HAM Inc** » Sun Oct 24, 2004 2:21 pm

As for specific output (ft.lbstorque/ cc) I don't think the TypeI with un modified heads would outperform a TypeIV with unmodified 2.0 914 heads. It would be hard to compare as variables such as displacement and RPM's would enter the equation. If comparisons were made on 2.0 engines (again with unmodified heads) I would expect the typeIV to come out on top, at higher revs it would probably be ugly. On a 1584 the typeI might have the advantage as the port volumes would favor higher velocities than the typeIV. But the typeIV would make power at higher revs.

When you start comparing the two engines with modified O.E. heads I think the results would probably be about the same as improvements would help each candidate. But the variables go up considerably as modifying heads changes everything and experimentation is required to optimize the combo, very time consuming. Perhaps a build off between a TypeI and a TypeIV following some guidelines would be amusing.

I've noticed quite a few myths and misconceptions about both engines on chat sites. I think it may have to do with the fact that some folks have a bias toward one engine or the other. They are both great little packages, each with different strengths and challenges. If you want a smaller displacement engine and your on a budget, the typeI is the way to go. If you want an engine in the 2.0 range the typeIV is a good choice for the budget minded. If you want to push the aircooled envelope in terms of displacement and/or revs, I feel the typeIV offers the most bang for the buck. It certainly offers the most potential in terms of raw displcement while utilizing the O.E. case.

70dragbug · Post by **70dragbug** » Sun Oct 24, 2004 2:29 pm

I think the TIV generally makes more power NA up to 6500 rpm,after that the T1 seems to take over.I haven´t seen too many TIV´s that are capable of going over 7500 without blowing.One reason for that may be that there are more cam choices for the T1?

Plastermaster · Post by **Plastermaster** » Sun Oct 24, 2004 3:27 pm

I think the TIV generally makes more power NA up to 6500 rpm,after that the T1 seems to take over.I haven´t seen too many TIV´s that are capable of going over 7500 without blowing.One reason for that may be that there are more cam choices for the T1?

The T1 vs T4 snivlery has always been an apples and oranges argument. I think the T4 has some qualities that lent the T4 to be developed as an autobahn car in Europe, and an off road engine as well as longer duration race engines in the US. (long duration meaning not drag racing). In all these aplications HP is not the primary concern. For that reason engine builders specializing in the T4 have not tried to squeeze every last horse out of the engine. The closest I have seen is Jakes E vers which are designed for light cars, but still there is the need to configure the engine for durability. This is all a bit of speculation on my part, but I just haven't run across anybody trying solely to produce max HP with the T4 aside from the recent 100 HP/Litre discussion. It would almost be a waste of a good T4 to not build it for durability and driving.

Ron

farmer · Post by **farmer** » Sun Oct 24, 2004 3:36 pm

In stock form there is nothing that beats a T4 head.
"Problem is, a little", that there are sooo many aftermarket heads for T1.
Big cc T4´s or smaller T4 revers do not need other heads on this side of 210 hp NA. Top notch porters/builders, (not me) can squeeze up to 230-240 hp (still absolutely streetable) out of a drastically modifyed T4 head. But that means the whole package must be on edge.
Most people do not need more than that.
T4 heads w. relocated exh. ports are Big $$ Remmele for one already makes them in smaller qty´s. And they can deliver serius hp. I just saw the newest edition last week. - Awesome !
T