JakeJr

Since I had already bought new gaskets, last night I experimented with the stock type gaskets and my Mikita and it seemed to work out okay.

I snapped the gaskets in using the plastic pins to hold them in place. Then used one of my fine tooth bits in the grinder and gradually removed gasket material and metal from the ID until the ID of the gasket matched the manifold/plenum.

Any material that tended to remain protruded I flattened with the bit also.

Seems to have turned out okay.

I re-installed the manifold last night and will finish the rest today; should be able to fire up this evening.

Thanks for the info; if I have any vacuum leaks I'll know to get the Accel gaskets.

Final numbers;

I opened the plenum diameters to 1-3/4" and "eye-glassed" the openings

I removed the divider wall at the plenum end of the runners to a depth of 2-3/8" and "eyeglassed" the openings; diameter @ 1-3/4"

I removed the divider wall at the manifold end of the runners to a depth of 1-1/2" and eyeglassed the openings; diameter@ 1-3/4"

I removed the divider walls of the manifold base to a depth of 1-7/8" and eyeglassed the openings. I increased the openings to an ID of 1-3/4".

Manifold divider wall length is now 5-1/2" which is as close as I can measure it with the manifold now back on the engine (I forgot, again, to measure it while it was off) Old age setting in!

Runner divider wall lengths are now 6-1/8"; the runner lengths, flange to flange,; were originally 10".

My garage looks like the inside of a silver mine.

Hope this helps.

Jake

------------------
1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

[This message has been edited by JakeJr (edited May 09, 2001).]

james_fearn

madmax,

did you lose any torque from from cruise RPM until 3000 RPM?

Have you had a chance to dyno it since the the loose rocker run?


James

dhirocz

iTrader: (2)

Bad-a$$ ! I am amazed at how much flatter the powerband is! I have a stock intake setup at home, and even though I can't use it (Vortec heads and the base is damaged), it might not be a bad thing to try, just for fun. A tree burr on a die grinder will probably take that aluminum out QUICKLY. I'm not sure if I want to try that with my new base (when it finally comes out!!! ), since the object is to have a somewhat flat powerband with an increase in top end over 4800 and no loss of low-end grunt(which you dyno chart shows). I'm using a SR so I'm not sure what I want to do. I'm not even sure if that base needs porting, considering the fact that I haven't even seen it with my own eyes yet. Wonder how well that setup would work with factory siamesed runners (have a set). Good low-buck alternative to aftermarket intake parts. Ideas?

Kick a$$ on the manifold man! That was pure genius, got any flow numbers? I bet that flows just as good as the aftermarket bases, and combines the benefit of the LT1 and TPI setups. Cool ****!


[This message has been edited by dhirocz (edited May 13, 2001).]

85MikeTPI

iTrader: (2)

Ok, I've done my testing and have full
data for all the tests here:

http://www.eecis.udel.edu/~davis/z28/winter01/dyno

And the specific tests of the semi-siamesed base at the below link:


http://www.eecis.udel.edu/~davis/z28...age010511.html


-------------------
My General synopsis on the porting is:
1) cutting a stock base will give you
increased airflow to bump up the
bottom end, and also move your
peak HP/TQ points up 400-600 rpm
above the stock 4800rpm peak.

2) Doing it to any of the high-flow
bases will exhibit the normal
power trade-offs of all runner-
length designs, trading low-end
for high-end.

Now IMHO:
-The stock base mod on a mostly stock motor
should be a nice $0 mode
-For mod'ed motors, a siamesed stock base
will not give you the low-end of a hi-flow
base
-For siamese'ing a base, consider it as
requiring a higher-stall TC (auto trans)
to utilize the benefits
-The siamese mod in no way replaces the all-
out performance of the miniRam, just offers
some of the same dynamics at no cost if
you're already invested in hi-flow TPI.

enjoy
mike


------------------
My Z28, ZZ4swap, TPI EPROMs

Guest

No james, the car has not returned to the dyno... it will within the next month I hope. I think it still has plenty of torque left, it will still burn the tires off the car. I know it lost some torque on the lower end, but I feel on my app (the Grand Prix) it was well worth the tradeoff.

I'm still deciding on my TA whether or not it was worth it, it has a stock 91 engine in it, and the midrange torque I think feels a bunch stronger with the stock base rather than the siamese base. I G-teched it a few times before and after, and IMO even though I lost a tenth with the stock base I think its basically just as fast. I cant drive well enough to say a tenth is any different at all I did notice it would rev much easier and liked to be shifted at a much higher RPM than before to get the ET's out of it, which of course has its good and bad aspects. I didnt see any change in gas mileage on it either, so I wonder if the increase in midrange torque on my TA is doing anything for me or not... I really hate to use the TA for any sort of comparison because I really feel the car isnt running right even though everything checks ok.

Ill post a little more about the TA later, Im at work and I need to get back to what I am supposed to be doing

Mike, thanks for posting that info!

MATEOZ28

I have one side done on my TPIS BIG MOUTH manifold, I felt the need to do this because my car was literally ripping the lugs off the rearend *ALOT OF LOW END* but after 4-4500 rpm I didnt have JACK! and carbed 305 almost beat my 400HP+ 383 stroker. I'm hoping to get some of my views up in here also on the difference.


I have one question though.... When you say you'll lose some bottom end torque that just means the TQ has been moved up the powerband right? I hope so because thats what I want.

I'll post some pics of mine tonight.

[This message has been edited by MATEOZ28 (edited May 14, 2001).]

85MikeTPI

iTrader: (2)

Yes you will loose TQ and Gain HP, while
at the same time shifting the peak TQ and
HP points upwards. Its the same thing that
happens with a miniRam, or rotating the cam.

I believe the only reason Max didn't loose
TQ in his test, is that the stock base is
so restrictive, that the increased airflow
actually was greater than the short-runner
loss.

My test showed a loss of 12ft-lbs while
moving the peak up from 4100 to 4300, and
a gain of 10HP, while moving it's peak from
4600 to 5300. (my HP curve is so flat that
"peak" is a misnomer.. 8-)

http://www.eecis.udel.edu/~davis/z28...age010511.html

mike


------------------
My Z28, ZZ4swap, TPI EPROMs


[NOTE! For anyone siamese'ing an aftermarket
base, note that you cannot port flat across
the top of the base, or you will have to make
custom runner gaskets like I did! The base
allows you to port beyond the eyeglass shape,
but the runners/gaskets do not!]



[This message has been edited by 85MikeTPI (edited May 15, 2001).]

Guest

I agree with the above... I did notice you listed the average HP and TQ and picked up a couple.


My TA... Well I dunno whats up with that car. When I bought it, it ran fairly good although kinda slow (peanut cammed TPI). So I changed the cam to some piece of junk old grind (204/214 .420/.443 280/288adv.) since the place I took my 85 TPI cam to for cleanup (it had some rust) and they did a nice job of turning it into a peanut cam . So thats how the other cam ended up in there, and it ran pretty good for about 2 years, and then it developed an overheating problem on long drives. There isnt a component on the car that wasnt checked or replaced after that mess. The only thing on there right now I havent replaced is the wiring harness, so I'm sure it probably is somewhat bad too. Since the cooling problem developed, it started getting bad mileage too. It also started going slower. It also started backing out exhaust bolts all the time no matter what I tried, and the passenger side was running a good 200 degrees hotter than the driver side. I used an infared thermometer and was measuring 820 at idle passenger side, 620 driver side. I had it down to a 15.2, and on a good day it would do a 15.6 after the engine or whatever went south. I put the siamese base on that engine for the heck of it, and it ran damn good with it on there. I gteched the car too many times to count before the swap, and it always hit about 15.2-15.3@89-90mph, which is about right. After I swapped it, I kept bringing the RPM's higher on the shift, and it kept going faster. I figured the engine was toast anyway, so I kept taking it up higher. 6400 in first and 5800 in second gave me the best results (and sent the temp gauge off into lala land) and I clicked off a couple 14's, 14.7 and 14.8 at 95 and 96mph. I tend to trust the ET more than the MPH, it seems the higher the MPH goes, the more off it is.
Then the 86 block finally gave its last effort, and I pulled it out. A Ford powertrain engineer came to check it out for me, and came to the conclusion the block was cracked from the driver side between the middle 2 cylinders, across the valley, and then on the passenger side across the tops of the lifter bores and up the back of the block by the distributor to the corner where the oil from the head drains down. So I pulled that, and put a used 91 engine in the car, it has the 'good' cam in it. It runs cooler, doesnt overheat with the AC on (which I could never use the AC before) although it runs hotter than I would like. It still gets terrible mileage... 11 city is pretty good and thats what I got a few weeks ago. I used the siamese base in the swap process from the 86 to the 91, and my 86 exhaust manifolds (which dont fit a 91 block well I might add) and it was definitely slower than the old tired 86 engine. I could only get it down to 15.0's at 91 and no better. Now with the stock base back on there, I am seeing 15.1 and 15.2 again, around 90mph. It definitely pulls harder in the midrange, especially at part throttle. I know I messed with the timing curve a little on the GP and it helped the response alot, it was a little soggy when I first swapped it but now its almost like it was. I suspect the TA would have benefitted from a timing change but I dont think it would have matched the stocker at 2000-3500. I think though that I will siamese the base on it now anyway

Another thing to consider is what the power increase is at the RPM's ranges you race at if racing is your consideration. A loss below 3000 doesnt really matter with a high stall converter, and if the powerband is wider you are better off. Losing power at 2000-2500 though should hurt mileage in theory since thats where the engine is probably at RPM wise.

If I can get the TA running correctly (and thats quite important) I will test it before and after if I do siamese the base. I wanna run it at the track, but that means I gotta fix the ill shifting trans too... something I am not looking forward to. Thats a big maybe with the TA, and I am not making any promises because the car is very tempermental. There is always hope though...

I think that covered everything I wanted to post

JucinGTA

Thought I would bring this ttt!!!Man what Great info!!!What would I do without this board? Thanks MadMax!!!

Fastcamaro87

bfd

------------------
87 IROC-z 305 TPI 5spd 10-bolt 3.73 posi ,8.8 Accel wires , bosch platinum +4 plugs,MAF sensor screens removed, gutted air box, ram air, K&N air filters,TB coolant bypass ,polyurethane tranny and torque arm mounts, K&N oil filter,Mobil 1 synthetic oil 20w50, futura GLS super sport tires 265/50/15 rear and 235/60/15 front mounted on 86 monte carlo SS rims ,

400 sbc and a 6 spd in the works

89IROCZZ4

wow. this sounds AWESOME!!! I have been looking around to see what I should do. Here were my options:

miniram (1200 was too much $$ for me)
superram (again, 1200 was too much $$ for me)
ltr/bigmouth/ported plenum/52mm tb (seemed ok, but didn't seem to produce numbers I wanted
carb setup (MOST people advised against this because of drivability)
How would you say this would work on my zz4? I have the stock tpi on it.

JakeJr

Well, others may have differing views, but I did mine several months ago and the improvement was awesome.

I had no idea how the stock arrangement was strangling my intake flow.

In fact, I went a lot farther with my mods and removed metal from both ends of the runners too, as far in as I could reach with my Makita.

Lose low end??? No way! The car actually actually pulls much harder from a stop now, but you've got to remember I'm running a 415.

So it's one of the best moves I've made with the engine, even better than going to a roller cam, and I've got MADMAX to thank for it.

Jake

------------------
1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

John Millican

iTrader: (1)

If anyone's interested I have a spare manifold for sale in the classified board. $50
SOLD SOLD SOLD SOLD


https://www.thirdgen.org/internal/cl...cfm?adid=11470

------------------
86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project

89formula422

Thought would bring this from the dead, i was thinking of doing it.

poorboy8

Its alive! TTT

cort351w

Would this help or hurt a stock 1991 LB9 (20,000 miles)? The only things that my car has right now is headers, exhaust. I saw some 350s, a 383 or two, a 415(?), etc., but no 305s. What would (probably) happen to my performance if I ported my tpi like madmax did? I have a 5-speed also. As far as the increased rpm's, what can the stock valvetrain handle? What about the stock bottom end? This looks like a great mod, but I'm only seeing results for 350s and larger.

Guest

If you look up a few posts, you will notice one from me about my TA. The TA is running a 305, in case that wasnt clear (I think I may have skipped that detail ) Anyways, with a 91 engine the car ran slightly faster with the siamese base but not by any means anything to write home about. You'd probably pick up as much by just porting the base, cleaning up the transition areas. It seemed to help alot more with the slightly larger cam I was running in the 86 305 engine that originally came in the car. I dont have headers on it, in fact its so close to stock right now its sad

If I were you, I'd skip it for now. I spent probably 8-10 months planning this and then eventually cutting up the base, getting the GP to the dyno, swapping manifolds and taking the car back to the dyno, so it was probably a year before I mentioned it. I am planning on doing this to the TA, as it sits right now except I'm working on getting the car running properly first. Its mostly stock, I think I have all of a different muffler, slightly higher stall converter, shift kit, different air inlet, and a ported stock base on there. Theres a few other things, but nothing thats making the car put down any more power. I figure I have a few months of tuning to do still before I take the car to get dyno'd, and those both come after I get the car smogged Still no tags on it, they are almost a year old LOL! If I come up with any good results on the TA I will definitely post them but I wont ask anyone to hold their breath.

85MikeTPI

iTrader: (2)

And just to keep this post alive, I've just
finished (re-)siamesing my Edelbrock base down
to 2.5 inch runners. (hard to compare what I
took out since most others are working with
stock bases) Before I had about 4.5 or 4.75"
runners left in the base and my dyno info is
here:

http://www.eecis.udel.edu/~davis/z28...age010511.html

and later here:

http://www.eecis.udel.edu/~davis/z28...age011026.html

The siamesing really moved the power curves
around and I could feel the top end increase
at the track, but since I'm setting up my motor
for 6500rpm duty, I feel I needed a much shorter
intake runner. (The MiniRam is 3.5inches BTW)

My base now is shown here:

http://www.eecis.udel.edu/~davis/z28...13baseporting/

and I will dyno and report back, probably in
Feb.

mike

Skweezn87

Good GAWD dude...

Rick

Guest

I snapped a couple pics a few days ago, sorry for the lighting (or lack of), it was late and I was putting the car back together (injector swap). Thought I'd post them since I've had more than a few requests for more pictures. I also started slicing up another base to put on my TA



Nice pics Mike. And I thought *I* was crazy! You know, a friend of mine told me I should just cut the divider out completely, but I didnt really want to taper the divider on the head.

HotRod

How do you guys think a supercharged 305 with L98 cam would respond to this? I really like this idea because it could save a lot of money. If you welded the low spots on the manifold you could port even more, would this end up being the same as an aftermarket manifold or are there other dimensions that are differant? Thanks,
Tyler

Guest

Sure you could weld it up, I did that to the stock plenum so I could put a bigger TB on there and have a decent transition. Welding costs money for most people though, so if its an option or not depends on how much you want to spend on the factory casting and if you can weld it yourself or not. The aftermarket intakes do have more material though, and some are slightly improved port wise that you would have a hard time doing to a stock base. I'm actually extremely happy with the difference on just the stock base, and it didnt cost me $400 either.

tpivette89

so, you guys are saying on a stock motor, this type of mod would show almost no improvement? my vette 350 TPI has a few mild mods, and im thinking about doing some port work on the manifold. the plenum is already mildly ported, and all other intake components are stock. if this shifts the torque curve higher, that would be great, cause as it is i cant full throttle launch the car without severe wheelspin. so, what i am asking is, would i see a noticeable gain at the track if i did this with the stock runners, or should i add slp runners to it as well?

86TpiTransAm

1 year and 6 days later this post is still goin' strong.

Popular stuff here .... at least the aftermarket companies haven't started profiting off it yet.

383GTABoy

Hmm i saw this post a long time ago when i had a 305 but now im looking at it again now that i have the 383 it seems like a lot better idea. HMM I know im starving for air pretty early but i dont want to go past 6000. Right now i have a complete stock tpi except for a bit of porting and some injectors.
Just curious what you guys think about doing this to my car and should i just go in 2 inches or do the "Madmax" and go crazy with the diegrinder. It is all stock tpi remember. and yes i know the sportmans were built for higher rpms than that. I got a deal

383GTABoy

Hmm i saw this post a long time ago when i had a 305 but now im looking at it again now that i have the 383 it seems like a lot better idea. HMM I know im starving for air pretty early but i dont want to go past 6000. Right now i have a complete stock tpi except for a bit of porting and some injectors.
Just curious what you guys think about doing this to my car and should i just go in 2 inches or do the "Madmax" and go crazy with the diegrinder. It is all stock tpi remember. and yes i know the sportmans were built for higher rpms than that. I got a deal

383GTABoy

Hmm i saw this post a long time ago when i had a 305 but now im looking at it again now that i have the 383 it seems like a lot better idea. HMM I know im starving for air pretty early but i dont want to go past 6000. Right now i have a complete stock tpi except for a bit of porting and some injectors.
Just curious what you guys think about doing this to my car and should i just go in 2 inches or do the "Madmax" and go crazy with the diegrinder. It is all stock tpi remember. and yes i know the sportmans were built for higher rpms than that. I got a deal

Pony Killer

Very INteresting, and Creative stuff i'd have to say.

I can See how that would yeild some solid gains,when the rest of the motor is modded along with it, ie done as a sort of package.

That's something id consider in the future.

85MikeTPI

iTrader: (2)

As my dyno numbers showed, cutting in about
2in moved my HP peak from 4800 to 5400.

I still haven't gotten my motor back together
to dyno it with the 5in cuts, but I'm betting
it will move it up further towards 6000.

If you want to shift at 5500-6000 and hurting
for air, the 2-3in cuts should work out great
for you..

http://www.eecis.udel.edu/~davis/z28...age010511.html

mike

383GTABoy

Thanx. Man this is gonna be fun. Wow tripple post sorry. Guess that teaches me not to use those crappy mac's at work

mrr23

took your idea a little further and differently. i left the divider where the runners meet, but went to within 1.5" of the head side.

http://www.fl-thirdgen.org/mrr23-5.html

also having it ceramic coated to keep the heat out. won't be able to accurately tell the difference because i'm changing cams when i do this.

palric

iTrader: (1)

Man this has been some of the best reading I have ever done on TPI modding.

Can't wait to get the dremel out...

RP.

Guest

Revived from the dead... again.

Anyways, I am still not having problems from this mod, and still enjoying the results. If you decide to do this, read the following post as well:

https://www.thirdgen.org/techbb2/sho...hreadid=140646

You can also try a search, theres a little more out there I know but the link I posted about covers it. Better safe than sorry.

mrr23

4 months later and i'm still not having any problems out of mine either.

3.1EyeCandy

iTrader: (3)

I may have missed it, but did anybody post about doing this to a stock L98? I'll have the car parked in the summer and this would be a fun thing to do.

MADMAX....:hail:

Chris89GTA

iTrader: (2)

man that is awesome dood... i am currently building a 383 and wanted to see what i could get out of it with a TPI intake still on it... i know some corvette guys are running 11's with the intake... so this is a big development for me... i am gonna try to do siamese it that way and see how it goes!!!!

Matt87GTA

Yeah, bout 4 months on mine and no problems....... cept for all of the missing rubber......

3.1EyeCandy

iTrader: (3)

Thanks Matt. I sure haven't seen you post in a long time. I'm going to have to get on the ball and start porting

aaronkark

I noticed someone mentioned that it would be a bad idea to siamise a 305 tpi with the smaller cam. I have an 88 formula tpi auto. Would a siamise on the plenum, runners or manifold help?

wyclefsirocz

if i was to pull the base out of the car and go to work with a dremel and open up the passages a little bit would this do any thing or am i just wastinfg my time, i don't want to try some thing as drastixc as you. i would like for a 10hp gain if possible along with porting the plenum. is this possible???

btcamaro

I was thinking about doing this to my car but what I am wondering is would it be better to siamese the top of the runners where they meet the plenum or to leave them alone and siamese the base.

92-tpi-z

so i take it you wouldnt want to do this on a 305 car. i just ordered slp runners and when i am putting on the runners i was going to port the plenum and port out the runners(i this okay to do). but i saw this. i still think this would be a bit much for my car.

mastrdrver

I was wondering if anyone has thought about siamese porting a set of siamese runners furthur down the top of the runner and shorting the effective runner lenght? I was thinking of trying something in the 13-15" effective runner lenght.

Spdfrk1990

yeh on a 383 i wonder if it would be better to siamese everything from the plenum to the intake.

grumpyvette

heres the siamess base, notice you lose at lower rpms and gain slightly at high rpms
first dyno run

http://www.eecis.udel.edu/~davis/z28...age010511.html

now look at the ADVANTAGE THE LONG FREE FLOW RUNNERS of the stealth ram, HAVE OVER THE SIAMESE BASE keep in mind they gained 16hp at 6000rpm by siamessing the base BUT THEY GAINED 39 ADDITION HP (total 56hp over the stock TPI) WITH THE STEALTH RAM at 6000 rpm and went on to gain a total of 66 hp over the siamesed intake (total over the stock tpi is more than 100 hp at that point . ( but thats really meaningless because the TPI stopped flowing any increased air at about 4700rpm......... yet youll have to admit a potential gain of 60-80hp gain aint bad for any intake swap

second dyno run

http://www.eecis.udel.edu/~davis/z28...age021105.html

Dyno Don

iTrader: (7)

Do a search for posts by Jerrywho, he siamesed his SLP runners exactly like you are asking about. The runners are now on his car and he is testing them.

DA 89 CAMARO

THIS STUFF IS GREAT.I DON'T KNOW WHAT I'LL DO WITHOUT YOU GUYS.KEEP UP THE GOOD WORK:hail:

bnoon

Holy old post Batman!!!!

88IROK

To say the least, I'm impressed and intrigued by what you guys have done here. The results speak for themselves.
I'm in the process of building a 383 for my 88 IROC which I bought with a blown up TPI 350 last year.
At this point, I have an Edl base manifold, SLP runners, GM plenum and 52mm TB.
I had no hesitation siamesing the Edl base 2.5" down and siamesing the plenum. All will be gasket matched to aftermarket large ID gaskets and see what the h3ll happens when I finally get it done in spring '05

Although I have no "before" data to compare to, I'm betting on some decent 1/4 mile times and maybe even some dyno results to show what it REALLY does.

Thanks to all the great folks here that stuck their nose to the diegrinder and the endless pursuit of more ummmpppphhhh !

327_TPI_77_Maro

iTrader: (8)

I too learned a lot from this thread, and went on to siamese my own base. I have a 327 with 2.02/1.7 valved 1960s fuelie heads on it. To say the least, the stock TPI does not do this setup justice. I used a horizontal mill with power feed on all axes and a 1" cutter to remove the walls on the stock manifold base, down to around a 2.25" depth. I then blended and hogged a ton of metal out of the base to gasket match it to the stock runners. I just drove my 327 tpi tonight, and the car has no problem revving strong to 6000 rpms under power. (4 speed manual). No doubt the siamesing and porting helped out here!