Ok everyone, I have a real 1st world problem.

I recently purchased a set of SLP first-generation runners. My initial reason for getting them was purely aesthetic. I grew up in a certain era that opening your hood to display SLP siamese runners placed your car on a higher spectrum.

I finally got around to ordering the bolts from Hawks and they should be delivered next week. Then it’s just a simple swap.

Of course, nothing is ever simple…

These are genuine never installed SLP first-generation runners that have never been ported. With that said, the casting is very crude. Many of the ports are not even round. So this is my dilemma, what to do?

I did not initially get these for any performance gain. But…I don’t want to leave anything on the table. But I’ve also done a lot of research on these runners and know that porting does not really translate into that much gain. I do understand how further siameseing (is that even a word?) the runners can shift forward the torque curve and I understand how this translates into more horsepower. However, I would hate to pointlessly damage the runners and/or waste a bunch of time and money for little to no gain.

My motor is a 383 and the details can be found here https://www.hotrod.com/articles/revi...stroker-power/

So assuming I only will be swapping the runners what do I do?

1. Go full retard and port match the runners to the gaskets and then send the whole thing out to get extrude honed? But does this make any sense considering my unported Edelbrock “high flow” TPI base?

2. Go to the local hardware store and buy some burrs and do some mild hand porting (to the gaskets) myself?

3. Just bolt the damn things on?

4. Also, is it a sin to hack up a set of original SLP runners?

Thanks.

 

I would bolt just the runners to the base and see how they line up. I have a camera that can be see I,side the runners, so I would check alignment and adjust from there.

 

I think you answered your own question. You bought these runners for their historical significance, not for performance gains. I would suggest that you just bolt the things on and cruise. Yes, if you port the runners, plenum and intake, you will feel performance gains. But at the end of the day, you have to ask yourself one question. If you sold the car, would anybody care that you have first generation SLP unmodified runners on the car. I do not know the answer to that question. SLP stopped making these runners years ago. I have a set of SLP runners on my TPI conversion that I siamesed. As an alternate plan, you could keep these runners and display them in a glass case, then buy a later generation set and port the heck out of them and install on your car.. You would then have the best of both worlds, the first generation unmodifed SLP runners in a glass case and another later generation ported set on your car. Good Luck.

 

The SLP runners were always considered 'meh' in stock form. They only come to life with heavy porting of everything. They look cool, and by cool I mean "aftermarket", but I wouldn't expect a huge performance boost from them, unless you massively port everything.

 

Interesting that this has come up. I am currently doing some mild clean up work on a set of SLP runners and opening the ports on a plenum to match the runners. I too always loved the look of the SLP runners too.

 

I wouldn't worry too much about modifying them. I know they are rare but just like the classic car market, rare doesn't mean highly desirable. Desirability is what drives value not rarity alone. We can point out many cars that were kept stock that later became valuable. Aftermarket parts, not so much. I would venture to say, modifying them in a way that makes them perform better but doesn't change their exterior appearance would actually add desirability to someone doing a vintage build and modifications.

With that said, I think you have to consider their long term value stock over what you will get out of using them as you want. I believe it pretty rare that aftermarket parts bring super high value. Especially when there are other options for period correct modification. I would port match them and clean them up, but not cut them open.

This is all just opinion. Nobody has a crystal ball to tell you what they will be worth in 20 years, or how many people will still give a crap about TPI cars in 20 years.

 

As you have seen, the 1st gen runner openings and exits are very crude. It wouldn't hurt to make more rounded openings to match the upper/ lower. I would also take a sanding roll and smooth them out all the way through for that warm fuzzy feeling. With the 2 runners on each side paired together, these runners offer the most power potential but they do need some work. imo

 

If I am on the same page I was thinking about something similar (but really did not want to put it out there for fear of the flame...although nothing could be worse then mentioning a Motive Power Bleeder...)

When you say sanding roll do you mean running a sanding belt through the inside of the runners like sanding floss?

Let's call it the poor mans extrude hone

 

https://www.harborfreight.com/sandin...-pc-62394.html

 

HAH! I used the same HF belts to resize some spherical bearings on my Z. I destroyed my buddies 12 ton press trying to get those installed.

 

Compared to?

I would think a mini ram offers the most Power Potential given the short runners being that it would be much more complimentary to a higher RPM cam to make power.

 

Oh no! TPI vs. the world...

In all seriousness, I am fully aware that there are numerous alternative/better induction systems. But look at my pretty avatar...

 

I've got some SLP's that have been cut open, ported from the inside, and rewelded. The plenum and base are max effort ported as well. ...and on my 383 I run out of breath at around 51-5200 RPMs. I wouldn't put that effort/money in it again. I say run it as it is and enjoy cruising, or, ditch it all together.

 

Most power potential compared to the 2nd design SLP runner.

 

The question of "Compared to What" was not directed at your response.

To be quite honest, I have a love affair with the appearance of a TPI. It was love at first sight. One of the best looking Intake Manifolds in history IMO... but aesthetics is a dumb thing to argue over as there are no quantitative measurements to compare, it is all opinion.

I am still TPI and do not plan on changing that... but who knows what the future will bring. As much as I am tired of LS swaps, a LS7 to have a 427 Camaro does have a nice sound to it.

I can see that.

 

I have to agree. TPI has to be the best looking engine. Anything else just doesn't look right when you pop the hood. I know that the TPI is a dinosaur these days. My cars that still have the TPI in place will keep them. I do have a roller that is looking for it's LS swap one day...

 

I think it is.

 

This does remind of when I took my Formula to a track cross event last month (single timed sessions on a road course). The millennial's would not even give my car a second glance (apart from the why the hell did you bring THAT look).

However, when I opened the hood the strangest thing happened. Although they did not acknowledge it, I noticed many just happening to walk by; sneaking peaks out of the side of their eyes. You could tell they had never seen a TPI motor before.

Then I fired up the motor. The sound of a lopey 383 SBC with long tube headers seemed to increase their conflicted curiosity. Their glances became longer but they never to made eye contact with me as I stood by the car.

I knew I had seen this behavior before. It was like watching freshman in high school first discovering cleavage

 

It also depends on what you plan on using the motor for.. for a number of uses you don't need to soon the motor past 5k also all the torque off idle to about 2,500 makes it a blast on the street and if geared right on the road course...
At least enough to tear the tread splices on my last two sets of BFG Comp 2's

 

I'm with you, hard to leave as cast alone but in the end I doubt it will add all that much to notice, then again why not Hog Em out??

 

This..have hacked about every TPI intake to death....are there gains...perhaps but not much..certainly not worth the money it costs...even DIY youll wonder what the hell youre doing.
If you take hte runners and base within their last breath and start epoxying yeah your gains wont feel as big as that pile of chips on the workbench.
Run em as is!