I have a ZZ4 crate motor that is about to go in my car with an Accel Superram intake manifold, SLP Runners, and 24# injectors with the stock plenum.

Is the stock plenum going to make the Accel manifold a waste of time or will the plenum not bottleneck and flow well enough for the ZZ4 with the Accel manifold and SLP runners?

 

On a long tube runner setup the plenum is the least of your concerns.

 

he's right. The intake manifold is the biggest bottle neck, then the runners. The plenum isn't all that bad.

 

OK thanx...

I do not have the tools or the time to port my own plenum. So are you telling me not to worry about it and leave the plenum totally stock? I am willing to spend $80 on a fully ported plenum from TPIS, but is it worth it being that I have a ZZ4 with stock throttle body, Accel Superram base, SLP runners, and 24# injectors?

 

If you left it alone it'd be alright....but if it's only $80 for a fully ported one from TPiS then why not do it? You might wanna look into getting a bigger throttle body also (after you have the runners, manifold and plenum taken care of), but you could also get by w/ the stock one.

 

As for paying $80 for a ported plenum....since you seem to be dead set against doing it yourself, yeah it's not an all bad price considering that by the time you buy a dremel and bits to do it yourself you've spent $50-60. I mean, if you don't match it at all then yes, it will be nasty. And actually, out of the box, SLP runners really need some help too. And thats when the initial buy in for something as small as a dremel pays off because you can take care of all the details.

No point in putting a TB on a car before it has heads and cam really. It's just not nearly the restriction that they are...

 

It's going on a ZZ4......heads and cam already taken care of

 

it's getting late, lol

 

If its only $80 then why not do it? You carry a good point. However, the motor was ONLY $3000 and the tranny was ONLY $1500 and the clutch is ONLY another $200 and the superram manifold was only $400 etc, etc, etc, you get the point.

Thats the problem with cars... when is enough, enough????

That is why... if the plenum is not going to severly restrict me then I'm not gonna get one. If it is... well then maybe I could justify spending ONLY another $80.

 

Point i was trying to make is that if you think you can just bolt all those parts together with no port matching then you're going to be running at nowhere near the potential of what you should be running. If you absolutely won't do the work yourself, then $80 isn't too bad of a price to pay to at least fix that problem. As cast, the stock runner outlets of the plenum are going to be smaller than the SLP runners, as well as blocking the barely siamesed section of the runner at the top. I can't quantify how far down on power you'd be if you ignored it since i don't think i know anybody with a modded TPI car that didn't port their plenum.

 

= Budget

Ed... I totally know what you are saying. But there is something called a budget. And it's not that I am against doing the work myself which has a negative undertone... I DO NOT have the tools or the time.

In addition, I was told that port matching things that air flows through doesn't do much of anything. Not saying its true, but that is what I was told.

And again, I have a budget. I can't get the superram manifold in, then get the SLp runners in, and then pull the plenum off the car and then send them to someone and spend even more money to port match all of them. To much more time and to much more money. These pieces put together will be far and away better than the stock pieces and that is what I was looking for.

 

 

If you didn't want to hear the answer, why did you ask the question?

I understand the concept of budget just fine. I don't understand the concept of spending thousands of dollars on parts and then not spending the $50 for a dremel and an afternoon of my time to make my investment work properly. The flaw in your logic is that you think just having these go fast parts is world's better than stock. There is nothing buget minded about slapping together parts and hoping for the best. What you have could be anything from a low 14 second joke to a mid-high 12 second warrior. The difference is in the details and execution.

 

The runner length seems to be the big limiting factor on TPI. Some people have solved this thru siamesed runners, etc. but you're just extending a smaller plenum and not solving the problem.

Runner lengths (quoted from Corvette Fuel Injection by memory so I may be off a tad):

TPI: 25"
LT1: 4"
LS1: 13"

Of the three, the LS1 makes the most power everywhere in the RPM range...but it's a completely new engine/head design so not apples to apples comparison.

The Holley Stealth Ram creates a means of testing the effect of runner length on the same engine/heads/cam/exhaust combo, it's runners are 15" (again from memory so may not be exact). I've got one installed on my engine now, and have dyno data from the TPI setup so I have a good means of isolating the effect of the different induction plumbing. I'll post dyno data when I finally get a session booked.

 

I understand you have a budget, but $100 ( i looked it up on TPiS and it's $100 for the plenum) wont make or break you. But like I said you can get by w/out doing it....but do you really just want to "get by"? Like Ed said. It's attention to the little things that make the difference. Like I said, I understand you have a budget, but you can still do the plenum in the future right?

 

When you're in the staging lanes, you can't THINK of enough "Little things" to do to get that one extra .1 lower on your ET. When its an option, PORT, PORT MATCH, Do the work, if you dont have the time... well DO THE WORK ANYWAYS, buy a dremel that is an immediate return on the investment, put it to work with a whole hour of your time... then in the future as you have more time, port/match more things, watch your ET drop, and realize it didn't cost you a thing...


Or go buy armloads of expensive *** parts and put your car together the wrong way and ask:


Gee why am I so slow for spending all that money

 

PORT THE PLENUM!!

I just did it on my friends '88 L98 Vette. Made a big improve ment throughout the RPM range.

Go to Home Depot or similar store, buy either a carbide bit or a file bit for a regular drill. The bit will run you about $2-$5.

Don't waste time with a Dremel because it will take you 4hours vs. with the drill and the right bit it will take 2 hours and do a better job.

Take your time and clean up everything. If you hear very high pitched noises while filing, then you are close to drilling through to a passage. Stop filing in that area.

 

Why are you starting to flame? I know what these parts do. The ZZ4 with stock TPI on it will do mid 13's nevermind with the parts I ordered.

Anyhow, I would love to port the plenum. I'm just saying when I am tapping close to $8,000 I have to stop somewhere and that is why I asked if it is going to REALLY restrict me or not.

Even if I did get the ported plenum... my next question is, they will won't be port matched. Is that a big deal when you are talking about air going through. If so, don't flame, but rather, explain why it is a big deal and then myself, as well as others, may learn something. Does port matching make any mayhem with the gaskets at all or do you still use the gaskets that you would have if it were not port matched.

Back to the budget, I do want the car to be fast, but my main goal is reliability and driveability. That is not to say that port matching will comprimise that. However, I am spending boat loads of money here and if I don't do something (port the plenum) and it will only cost me 1 tenth, I can live with that. Especially considering that the plenum can be easily popped off and ported at a later date.

I would like to thank you all for your input and I welcome anymore that you may have.

 

I wasn't flaming you, i thought it was a simple observation. As for explaing why it's a restriction, i guess you missed the above post by me?

Ad as i figured you have a tremendous flaw in your logic. A ZZ4 with a stock TPI haphazardly slapped on it will not necessarily run mid 13s. Yes, it CAN run mid 13s and even a little better with the stock TPI parts, but thats when it's ben put together properly. And just because you're starting with 'better' aftermarket parts doesn't mean you will start out ahead considering how poorly port matched all the parts are. A day or 2 with a grinder of any nature would be an easy 30-50hp

Again, this isn't a flame,. it's just a wake up call. You asked a question and admittedly it has grown into a larger issue of port matching all the TPI parts, but they only came up because it's an example of why you should buy a dremel/grinder rather than pay for just the plenum to get done. But the answer to your question is that as cast those parts don't work close to optimally, and nobody i know would spend $8k on engine upgrades and then give up on the important finishing details.

The question back to you is....$8k for 101mph or $8050 and another day of work for 106? I KNOW what all my gearhead friends would say....

 

I could understand this debate if it was about whether or not to plunk down the cash for a super ram, or even whether to pull the whole top-end off to port match the intake manifold runners... but we're talking about a plenum here. You can give back your SLP runners if you don't port the plenum, because they are worthless if the plenum isn't opened up to match. Might as well get rid of the accel base too because if it's downstream of an unported plenum, it's not doing much.

It sounds like you put a ton of effort and money into this project. Going half-assed on something this unbelievably cheap is just amazing. It's like building a beautiful house and then being too cheap to buy lights for it and deciding to use candles instead.

Go find a friend with a dremmel (or better yet, an air powered die grinder), go spend $5 on a metal bit & a can of WD40, and port your plenum.

 

Let me put this in a way that wont sound like i'm being an ***. You say you've spent tons of money on this right? Well if you dont port your plenum, then the intake manifold and runners are useless....that's $700 down the drain...all because you dont wanna spend a few bucks and a few hours to port the plenum. See what we're saying?

 

Don't be pennywise and pound foolish.

The little things make up as a whole more than you think. ANY little place that can be modded,improved,replaced,etc will help.

Figure this:

You and the car next to you have the SAME exact setup. The other guy did the little crap like porting the plenum,t/b bypass,remove maf screens, etc.

The other guy will take your money.

 

Ok... I'll port the plenum. I'm not gonna port the base or the runners though. The plenum, if I can find the TIME, can be done by me. I do not have the know how to port match intake manifolds and runners and whatnot. The plenum I can do though... and even still its not gonna be "port matched." How does one do that anywaY?

 

If you dont wanna port the base or runners that's not a thing. If they're aftermarket, MOST people wont touch them. And as far as port matching the intake to the heads and whatnot, from what i hear, you wont notice a difference anyways...maybe a .001 lower on ur ET. To port the plenum, you just use the gasket from the runners for a template. And smooth out any obstructions in the from TB part. I dont know exactly how to explain, but I think there's a tech article on how to do it.

 

Not exactly


Doesn't work as a "template" for the INSIDE of the plenum

 

ir0cz and all... thank you. I know inside the plenum you grind away any obstructions... and then to match the plenum to the runners you use the runner gasket as a template. Understood, thank you.

I am not going to port the runners or the base. I totally understand and agree with Ed that porting them as well will get me the max performance, but that is not my main objective here. I got rid of the stock runners and base because they really restrict and the aftermarket parts will do better (but not max performance without port matching). I will find a way to port my plenum one way or another. I just can't wait until this whole thing is done so I can drive it.

Question though: Are the plenum and runners EASILY pulled off after the whole engine is assembled and installed in the car?

 

Glad I could help. The plenum is pulled off VERY EASILY. The runners are a little harder as you have you use extensions and such....but still not a huge pain. Let us know when you get it all together and running, i'd like to see what your setup will do. Good luck.

 

Plenum and runners can be pulled off in well under an hour once you've done it a couple times. I'm getting so good at it i had the plenum and runners off and on twice in ~ 2 hours a couple of weeks ago chasing a vacuum leak after i put my siamesed base on (working quickly is what led to the second stanza, i had all bolts in and started tightening before i realized i put the runners on the wrong sides )

Hell, it'll be interesting to see what it runs with everything untouched and then again with it all opened up and matched. Like i said, i've never heard of anyone doing things in such a 'backwards' way, lol. Try to get some repeatable results so you can do a fair comparison and let us know.

 

Hey...

I think I may just port the plenum and see if I am capable of matching the plenum to the runners. That is the most I will do but I am thinking about doing it before I put it on. The guy thats installing the motor and tranny says he has a machine shop and everything there so I may just tell him to do it for me that way it will be done at once.

I am a FIRM believer in doing it right the first time, which is why I posted and asked whether the plenum was a huge bottleneck or not. At first, I was getting mixed results... some said don't worry about it, some said you must. That happened to open other cans of worms such as port matching the base, etc.

As I said before, I believe in doing it right the first time. But the problem with this project is that I have been trying to do so much of it right the first time that the price tag is climbing to close to $10,000. That is why I got to the point of picking and choosing priorites of what must be done and what can be done without. I knew that getting a new intake manifold was one of the things on the must list. Porting was much lower on the list, but given all the helpfull input from the members of thirdgen.org I think I will FIND A WAY to make sure that the plenum is ported and matched to the runners.

I can't wait to have this all done and see how it responds. The only thing I'm not clear on at this point is whether I should get a new fuel pump or not and whether the stock PROM is gonna be real bad or not. Regarding the PROM though, I am definetly gonna leave that as is for now, and if it doesn't run well I will buy the PROM burning equipment so that I can burn as many chips as I want and learn more and more as well.

If I do say so myself, once this is all done, it's gonna be one hell of a car! I am sure I will continue to be on the board frequently as I find more questions to ask.

 

here's some advice....when you look at how much you've spent on your car....just look at it this way. My $10,000 car can beat a new $25,000 car....makes your $10,000 look like beans doesn't it? And you get the satisfaction of building it rather than buying it.

 

I would strongly recommend that you pull the runners off and clean them up too. I know you don't want a major project, but when I matched my runners up to my plenum, I discovered that the inside wall of the runner tubes encroached on the plenum opening by up to 1/8" in places. You really need to get rid of that lip on the runners to get a good transition between the plenum and the runners. It's only a very small amount of grinding on the opening to the siamesed tubes.

 

One more piece of advice:

When reinstalling the plenum, make sure the bolt holes are lined up properly!!! Be very easy when putting the bolts back in. If the bolt stops or gets hard to turn, back it out. You WILL strip the threads very easily and will have to heli-coil it.

Also, put a very small amount of anti-seize lubricant on the ends of all bolts going into the plenum. Makes it easier the next time you take it off and you can torque the bolt down just a little more than with out.