Aloha!! again my Corvette Brothers and Sisters around the world!! I have a tech ques. How much of and emprovement will I get by porting out the plenum of my 91 L98? And how do I go about achieving this wonderful discovery of mankind!! Please, Im a picture man, I need pictures. Again, Mahalo Nui Loa! :crazy: :lol: :confused: :jester

 

The upper plenum is easy...just pull it off and use a die grinder ( or even a dremel if thats all you have ) to remove the ridges directly behind the throttle plates so as to not interferre with air flow from the throttle blades.

Other than that, unless you are using large runner tubes, porting nothing else in the upper plenum will really help.

 

I've been too lazy to put up the recent pics but have a verbal on my site.

You likely won't feel any difference but it's a nice project and may net some small increase in performance.

 

Thank's for responding. I failed to mention that I do have siammesed after market runner's, so does this info make a diffrence in your or anybody reading this forum's opinion? The gutted center cat, no muffler deal & the usual mods have also been made along with the Ed Wright's custom chip and very near future gutting of the pre cat's. If you or anybody can post picture's, I really would appreciate it, I do not want to go about doing this blindly and screw this project up. Head's are going to roll.... mine.... courtesy of my beautiful wife..... OH!!:eek: Hi Honey (Who's presently standing over my left shoulder!!)No I did not screw something up on the car again... Have I told you how pretty you look lately? No Im not spending time doing unnecessary things to the car:rolleyes:, these are VERY IMPORTANT things that need to be done. Yes honey.. I no.. I Love you to. Wheew.. sorry about that guy's! So, where was I... oh yeah ..rolling heads!!... mine!! So if it's possible please post the picture's for me. Mahalo Again!! :jester :D :lol: :blueangel: :seeya :eek:


[Modified by Double Clutch, 2:23 AM 7/5/2002]

 

Hey there.
I have had 2 sets of ported plenums on my car with the 3rd one installed tomorrow (siamesed with SLP runners, and intake).
If you port your plenum very well, and I mean totally smooth out the pathways from the TB to teh side port openings, and shave away a lot of the 1/2"+ material between the ports, you WILL notice a difference.
When I did that to the vette about 6 years ago the first time, ALl the mods I had was an exhaust and a custom chip, and the car outran the current '96 SS Camaros all day, and pulled strong to 5k rpms, as before It ran outt abreath after 4600rpms. It is one fo the simplest mods you can do to the car. (Just be carfull nto to grind too much away thats all.
I took off my currently ported intake yesterday, so I can take pics for you if you want. Email me and I'll send you the pics.

 

Here's a link to a post that I ran a few weeks ago. The first response from Flame Red has a great link with pictures. The only area that it doesn't point out is the hump on the bottom between the 2 openings. You can take a lot off there. Make sure you read all the replies in the thread. It will give you a good idea of what to expect. One more bit of advise. Put the plenum bolts back in the same holes you took them out of. Also, make sure there tight, but not too tight. You don't want to strip any of em. Also take the time to clean your TB...front and back.
Let me know if the link was helpful, and post your results when your finished.
Good Luck!!! http://forums.corvetteforum.com/zerothread?id=319424

 

Howzit Mr Nuke!! My e-mail is zolarcomics@hotmail.com. I hope that you did'nt go through that trouble of takeing off your plenum just to show me picture's, if you did I must have sounded really desperate!... I was!! and I am very greatful whether you did or not!! Mahalo!! And to you Triple Black for that artical that you forwarded to me. Much Mahalo's. I will let you guy's know the result's soon! :cheers:

 

Guy's, one more thing. Where the siamese port's meet the plenum, now, don't think I'm stupid or something... but... can I grind the 2 port holes on the plenum until they to are saimesed to match the runners?!?! :confused:

 

I don't see why not. Just make sure you modify the new gaskets...you did get new gaskets right? :D

 

Yup.. Sure can. Every bit helps on the intake for more rpms.. You want to be most careful on the lower intake manifold if you siamese them, as if you go to deep you could port right through the intake (it is angled). I already have theintake on the vette. I'll send ya some pics.

 

Ahhh?!??...New gaskets?!:eek:.... Ah..... Yes.... Ah... Triple Black!!... Ahh?!?....Of..Ah...Of course I did...:confused: (Honey... on that shoping list... yeah, the one I wrote out.. can you add on it new intake & Runner gaskets?!... Please?!!) :lol: :jester

 

So MrNuke Is there any history behind the nick name, or just somthing that you thought up... just wondering. How much thenths in the 1/4 mile would you or TripleBlack think that I would be able to knock off? Does it add horse power or torque, or free up what I already have? Also will my miles per hr raise alot, alittle or barely any? Im I geting on both you & TripleBlacks nerves by asking so many ques? :D I do appriciate all of your help in this never ending project!! Mahalo! :seeya

 

I think he is using 'nuke' to refer to his Navy job. When I was in the navy, I was referred to as a 'nuke' as well. It's the common term given to those of us who operated the nuclear reactor plants. It was probably originally meant in a derogatory sense...but the name fit and we all accepted it.

One thing is for sure...It's not a badge many people are capable of wearing, as about 80% or more of all who start out to be 'nukes' are dismissed or fail out of the program. The difficulty level was rated by a 60 minutes special as on par with Harvard Law School...if that means anything to you.

I am proud to be referred to as a 'nuke' even though I am no longer in the Navy.

 

Some people also used the term nuke to refer to the weapons guys who handled, ...ahem..., special weapons.

Of course, it was a little different...those guys were kept in the dark about what they really were doing...but the real nukes ( us ) knew more about what was live and not than they did.

 

BBA, you are kinda close. :yesnod:
I did some work in Groton (New London Naval Base) on some of the systems that went into Seawolf 1 and 2 few years back.. The Name Mrnuke I've received from friends due to a small mischief I pulled with some officers who were getting trained on the new systems. heheheh
Anyways, here are the pics...They are around 35K a piece.

Just a bit of info :

The left plenum on the pics is the new one I was working on today, but I haven't done the finishing touches and painting of it yet (matte-black). The plenum on the right is the first ported Plenum i was using. I put them next to eachother for comparisons. I forgot I actually have a 3rd FULL intake unported but oh well, too late now for pics.. I'll have new engine pics tomorrow when everything is installed.. And new performance #'s too..woohoo...






[Modified by MrNuke, 10:43 PM 7/5/2002]


[Modified by MrNuke, 10:47 PM 7/5/2002]


[Modified by MrNuke, 10:50 PM 7/5/2002]

 

2C, not getting on my nerves at all. Just wish I had an answer for you on this one. You should feel a slight difference in throttle response. As far as HP, top end and 1/4 mi, I'm not sure, but it can't hurt them. Wait till you see how restricted the openings are. I saw Mr Nuke's pic's and they look good, but I took a lot more off the sides...a lot more. And I also went to town on the center hump, and smoothed it all out with a sanding bit. When do you plan on doing yours? If your looking for another free mod that WILL make a difference, cut your shroud just below the air filter. Along with a K&N and a hevily cut lid, you will see major top end/tourque improvements. Check out the last entry on this link. Also getting your car tuned with a laptop will blow you away. You'll be blowin the volcanic dust off those Hawiian Chiquitas :crazy: http://forums.corvetteforum.com/zerothread?id=316375

 

Thanks so much for those pictures MrNuke!!! Now I have a much better understanding of what I have to look for and do to the plenum!! A lot of work!! Triple Black, I plan on doing this task sometime this week, it will have to be on a day that the car can be shut down for the day. What did you use, tool wise to work on yours Triple Black, and also yours Mr Nuke? I have a high speed dremal tool with an assortment of soft metal grinder attachments, but it looks like that Id have to be able to reach deep within, and I don't think that I'll be able to with the dremal, but, I do have a jack hammer? :jester And how long (average) did it take both of you to do this job? Triple Black, when you say cut the bottom of the fan shroud, how much off the bottom should I cut? and should I worry about the water intering the engine via through the air filter and causing the engine to seriously fail?? :confused: theres a term for the failure, but what it's called slips my mind at the moment. :rolleyes:

 

One more thing that I forgot to mention, I have a 91 L98 motor, and as far as I know, (correct me if I'm wrong) I dont have that capabillity to plug in a computer to reprogram my car?:confused: Im I correct or did my mother drop me on my head when I was a baby 7 times to much? :jester

 

Well, using a dremel will take a loong time to do it and a LOT of bits..
I used my father's machine shop to do the work. The reason I left some material on the openings, is that I did not modify the SLP runners, but left them they way they came stock. I wanted to try them as they shi for a baseline.. I must say though putting in an SLP runner is a PITA.... Doesn't fit without removing the fuel-rail/fuel lines unless you grind it down on the bottom of it. (They leave a lot of material on it).. Very poor job from SLP I must admit..

 

DC, I used a Dremel, 3 bits, and WD-40. One bit was barrel shaped, one was tapered and the other was a round sandpaper bit It was about 1-1/2" dia and it was made up of a bunch of flaps. I actually used 2 of these, one for each opening. This was the last step to smooth the surfaces. The WD-40 kept the bits from dulling. Make sure you pull up that linc that I attached. The firs entry by Flame Red has a great linc with pics of the plenum and bits. At the end of the linc it gives you a detailed description of everything I did and how long it took me. Let me know if you can't find it. It will really help you out, and it details how long each step took. I took about a day and a half, but I also took off the TB and cleaned it front and back, cleaned and set the IAC, cleaned the runners and fuel rails with a toothbrush, and other things like that. I started Friday night around 5:00 worked till 2 am, Then from about 10 am Saturday till 10 at night, but I work slow. It also took me forever to get the plenum back on...like 2 hrs :eek: I just could not get it lined up, and my back was killing me.
As far as the shroud, I'm not sure if 91's are the same, but when you take your air box off and look at the shroud, there will be a flat spot about 3" wide by about 2 1/2 foot...should be easy to see with the air box removed. I cut that off, which allows outside air in. I even ran a 6" air deflector from the air dam to the filter. I have checked each time I've driven in rain, and no problems. Let me know if this helps.
Steve