Dark Ember

Just another post about siamesing the runners, but this one comes with timeslip data. I am going to the track on the 20th(next Friday).

For those who dont know, here is a post detailing the information about the car's current modifications:

stock L98, auto, 3.23 gear

air foil
underdrive crank pulley
SLP Runners
1.6 roller rockers
custom ram air using z28 air filters
adjustable fuel pressure regulator set at 55psi(preset before I got the car and running stupidly rich)
1LE aluminum driveshaft
magnaflow muffler
battery relocated to trunk for traction and for the ram air

ET from Houston's tripple digit heat wave in June of 2011.

60ft -- 2.098
330 -- 5.93
1/8 --- 9.111
mph -- 77.28
1000 - 11.864
1/4 --- 14.176
mph 97.59

Alright now for the good stuff. I ported and polished the plenum, runners and the base. I also gasket matched the heads to the gasket. The ports are polished smooth to the touch but the camera, which despite being crappy quality pics, still managed to show the imperfections of the port job. Wherever the die grinder could not reach, the rotary tool + flex hose did. Unfortunatly the dremel diamond bits did not port as smoothly. I used steel wheel brushes for the polishing. Below are stock vs ported pics.

I highly reccomend a die grinder to port with. Its literally 25 times faster at cutting than my black and decker rtx(dremel). I used a Silver Eagle SE350, .33hp, 20,000rpm fed by a 60 gallon compressor with 10.2scfm@90psi, which still could not keep up. These bits are the real deal.



Here is the stock assembly + the Runners.



And the finished product. I also polished the outside a bit and painted the throttle body plate.




Unported Plenum and Runners with fel-pro stock replacement gaskets:




After the port and polish:

Dark Ember

The runners were a pain to port out due to the 180 degree bend.
Also the SLP's are a bit dissapointing because the port openings are about just about the same as stock.

SLP out of the box:



After I siamesed them more.

Dark Ember

The stock base almost makes a soft S shape. My goal was to straighten out the port as much as possible. There is a ton of extra meat on this thing to port. Instead of making the ports huge though, I mostly focused on making it straight. The ports did get enlarged a good amount but not all that they could have been. All of the gaskets were enlarged to suit the larger ports. Since my engine is internally stock except for rockers and intake, I thought it would be overkill if I really hogged it out.

Stock base ports:



After the port it was a much straghter shot for the incoming air. I had to be careful not to open up into the other ports as I did this. The die grinder was tearing through this soft aluminum FAST.



Here is the stock base port from the bottom up with the straightest camera shot possible:






And the stock base from the top down:



And again after the port:

TTOP350

iTrader: (8)

Checkout this thread. I have a set of my older almost finished ported runners pictured later in the post. You can also see the one of the bits I use. Its for aluminum and plastics, the ones your using are for cast iron (I think). Happy porting !!
https://www.thirdgen.org/forums/afte...p-runners.html


Oh and in your pix it looks like the upper plenum gaskets are on the wrong sides.. Its a small thing but there are correct sides.

305sbc

iTrader: (3)

Comparing a July run to a January run will not give you any test data of any worth, so forget that. TPI cars normally gain 1/2 second or more in cases like this just due to the air quality alone.

TTop is right. Burrs for Aluminum have bigger gaps between the cutting teeth so they don't load up with the Aluminum.
Often a burr made for Iron will load up with Aluminum, get out of balance and bend the shank, and/or destroy the bearing in your tool.
Electric die grinders with a dimmer-switch (speed control) are ideal for porting Aluminum or plastic.

That's not a bad job if this is your first porting experience.
Thanks for posting the pictures.
Look forward to the results, - I'm sure you will run a good bit faster.

Dark Ember

I did not have any problems with aluminum building up on the tools as long as I kept the spray bottle of WD-40 handy. I don't doubt that an aluminum bit would be better suited, but I already had these and they worked well enough to put a smile on my face. Also the electric die grinder would have been preferred since I would not have had to stop so frequently, but just as with the bits, I already owned the air powered grinder. It is a variable speed grinder though.

The plenum pic with gaskets has both plenum gaskets in the pic so that you could see the difference in size from the stock set up against the runner AND the Plenum. It was only done for comparrison purposes, I'll definetly have that right when I install it :P

As for the winter/summer spread. Yes, thats unfortunate. The former pass was taken late in the evening when the temperature had cooled to the high 80's. However Texas has perhaps the most desireable winters in the country(depending on your opinion of the seasons). Daytime temps are when I will get the new run and that could very likely be a nice 70 degrees, so less than 20 degree difference. I will be doing my best to minimize the temperature change. If the temps on the 20th looks like it is going to be arctic I will have to test it again at a later date.

I looked all over this forum about the siamesing posts. I read as many posts about siamesed runners as came up in several searches, but I never found a single track result. Are you sure on the 1/2 a second thing? I did see a few dyno results but those were also on engines with aftermarket heads and cam. That doesn't mean they arent out there, only that my searches did not yield any. I also noticed that because most of the engines this is done on are more modified than mine it would be something new to show what mostly stock engines can gain.

305sbc

iTrader: (3)

It's DA (Density Altitude) that you go by, and not just an air temperature.
DA uses temperature, humidity, and barometric pressure to calculate air density. Even if you're within 20*F the air density is likely to be drastically different due to the humidity and barometer.

The 1/2 second due to air quality is in reference to just that, - the DA difference experienced in winter as compared to summer. In Texas you get more sun in the winter, but your air still comes from Canada.
Some tracks will give you the current DA on your time-slip for reference.
If not, then you can usually find out from another racer who calculates DA for tuning changes, or you can sometimes find it online.

If you're going to do testing, then always use a DA reference.

Long runner intakes like the TPI are very sensitive to DA changes, - more so than short runner intakes. It is common for TPI cars to run at least 1/2 second quicker on a cold winter day, and I have seen 1 full second quicker on many occasions. It would be more well known, but most tracks in the North close for winter.

You may be able to do a search on "Madmax + siamesed" and find some test data from many years back.

Dark Ember

I am aware of density altitude, and used to live and run at rocky mountain raceway in utah where the DA was occasionally over 10,000 ft. I spoke to a track official at Houston Raceway Park(now royal purple raceway) once about it and he told me it was relatively consistent. He said there was one fluke day that it had dropped to -2000ft though. I suppose I should have verified the day of the last test and again on this one but it just sounds like you are splitting hairs man. Its usually no where near that much different. My LT1 Monte lost less than a full second from going from HRP at sealevel to RMR at 4400(closer to 10k DA). Thats about as extreme of a DA difference as you will find. You can use your full second density altitude argument to nullify just about every mod. Example: "Hey guys I just put a set of headers on my truck and I ran .4 tenths quicker in the et."

"Pfft, that doesnt say anything, it probably made the truck slower and density altitude was the only reason it got faster".

Yea you have a bit of a point man, but live and let live a little. Do you start this DA discussion with someone every time they talk about an improvement they got from a modification?

305sbc

iTrader: (3)

Ok, no need to get defensive. I wasn't trying to discount your efforts.
Looking on dragtimes track weather records I see that your track is much more consistent when it comes to changes in the air density that what I'm used to. Please forgive me.

You said there is a lack of data for tests like this and you are right.
What I added was an effort to improve the quality of data for the benefit of those who search and find your results.

If you would consider posting your timeslips from both before and after your modification, then there will be very little grounds for arguing the results in either direction. Your date and time for the run should be visible on the timeslip, thus making it very easy for next guy to look up the weather data from dragtimes and know the DA for each run, and the correction can be easily calculated right there on the dragtimes weather page. No funny stuff, & no petty arguing.

I was not trying to discount any gain from your modification, and I'm sorry if that's what you're used to here. There will always be a correction factor for the DA though, and it would be quite a stroke of luck to match a July DA with a January DA, even at your track.

For example, a typical DA for around 5pm at your track in July was around 2800 ft.
If you had run your car there this evening about that same time the DA was -944 ft.

That is about a 4.23% correction factor for ET.
On a 14.0 second car that is a 0.59 second difference.

Good luck with your test runs.

Dark Ember

Hey man, I just reread my post and ya, I guess I did bite your head off a bit. Sorry about that, I was dealing with some other rl junk and sat down to cool off and read some forums and misinterpreted your post. It would be best if I could get all the DA figures for testing purposes and more accuratly find out what this port job is worth. How did you find out what the density altitude was on a given day at that track?

My scanner is currently not communicating with my pc so a crappy quality pic is the best I can manage until I get to my parents house to scan it on theirs. Looking over all of my slips though has reminded me of the dates. It was actually June 10th that I ran the earlier posted time at around 7:30 and again I went to the track on Sept 9th, and ran an almost identical time to the june 10th run. 14.181@97.15mph. The best slip is cut up to fit into a little car photo booklet that I take to car shows. So the exact time of that pass is lost. But the track opens at 6, and starts racing around 7 and goes until midnightish, but I usually leave by 10:30 at the latest. The sept 9th passes were also around those same times. My track cuts the slips in half so you only get the time if you are in the right lane. But both nights passes would have been between 7-10ish.

Here is a scan of the time slips. Starting at the left, the first one is cut to fit into a little photobook of my car, but it's from june 10th. To the right, also June 10th. I returned to the track on sept. 9th.

DENN_SHAH

iTrader: (1)

305, im kind of lost on this "In Texas you get more sun in the winter"

305sbc

iTrader: (3)

Sorry, I should have finished that thought to make it more clear. I was comparing Texas to Illinois where I am. Houston is a lower latitude than Saint Louis, and so gets more sun exposure in winter than we do.

I think our high yesterday was around 18*F. While a car would run very fast in that sort of air, the tracks are closed.

______________________

Go here:
http://www.dragtimes.com/da-density-...t+Weather+Data

and you can look up the weather conditions for any date to get your DA for comparisons. It's a very handy site to use.

It says the DA was 2336 ft at 7pm on 10-June-2011 in Houston.


At the track here (GIR) the DA was 2717 at the same time you ran.
Right now it's more humid that normal (for Jan), and our DA is still -1655 ft.
So you can see we have big seasonal changes.
A long runner TPI car, especially one running on the rich side (like most are) will turn into a completely different animal here in winter.

(TPI issues in my environment)
The DA correction calculation does not take into account the added effect of the long runner length of TPI, nor can it factor in individual tunes, - say you are running 20% richer than the lean limit of your car. This means that in many cases a TPI car's performance will exceed the predicted numbers in the environment where I am right now.
Another factor when running with closed-loop computer corrections is that the fuel trims will adjust when our seasons change. The ECM does try to make proper corrections to follow air density changes, but it cannot do so perfectly. Even when running open-loop tunes, these sort of factors make testing more difficult in my environment, and it would be handy if the air quality was more consistent throughout the year here.

If it sounds like I'm splitting hairs, it's because I'm a tuner. I guess it can take some of the fun out of it though lol.

DENN_SHAH

iTrader: (1)

ok, that makes sense to me now.
i don't think i would care to make a pass in snow.
i bet your looking at our temps down here and wishing,.. LOL

BuzzLOL

.. Looks like you were already running nearly as quick as a stock LT1 Camaro now... will be interesting to see what your porting does... not sure if you shortened the runner length enough to help much at higher RPMs...

Dark Ember

Updated time slip pics to actual scans.

Buzz and Denn... MonteSS.com forum invasion hehe. Buzz, what really excites me about this is the prospect of going high 13's through stock cast iron exhaust manifolds and stock cats. Long tubes, new Y-pipe, high flow cats, and a tune are next.

DENN_SHAH

iTrader: (1)

hey Dark.
the weather channel is predicting 70s and rain next saturday. hopefully it will be 70s but without the rain.
with better temps and the intake work, i think you should do it,... if you can hook off the line.
here is hoping the track prep is good

i had intended to mention this sooner, like when you said you were going to open up the intake but i got side tracked and forgot.
for doing the base, a good 6~8 inch long bit is well worth the money.
i started out by doing my spare plenum just to see if it would make a difference. i didn't do anything radical, just cleaned up the entries behind the throttle body and into the runners.
with everything factory stock i didn't really expect much if any change, but i picked up just enough RPM that the motor is still pulling into second gear.
before i could feel it nose over just before the 1-2 shift.
so that got me into wanting to do my spare base.
i started on the base with the short bits. but i soon got tired of nicking the walls with the grinder and bought a long bit.
in the time it took me to do 2 ports on the base with short bits, i did the remaining 6 with the long bit, and they came out better.
now i just need to get some motivation and put the base on along with some other very much needed work to my car.

BuzzLOL

.. 12's with the long tubes will prolly be fun as well...

ninetyone

iTrader: (2)

Have you ever considered making 4 half inch spacers out of plastic by tracing the gaskets? This would extend the slp runners a little longer than stock. I wonder if it would increase the low end torque along with what ever gain you got now?

ninetyone

iTrader: (2)

So, what did you gain in the 1320 by porting and adding those slp runners?

Dark Ember

Won't know until friday. As for spacers, it would probably improve low end a little because it would further increase the runner length and therefore velocity of the air. That is somewhat directly counter productive to siamesing the runners though. These engines dont need any more runner length, but less. The top end would likely suffer even more due to the spacers.

2 days until the track results And Buzz, like you said, I am really hoping for 12's once I do headers and a tune.

Dark Ember

Track results are in. Timeslips will be scanned in on Sunday(my scanner is still down)

Just to review I am typing all timeslip data in this post.

Stock intake June 10th 2011: 83 degrees, 1950ft Density Altitude, 94.42% Relative Density

60ft -- 2.098
330 --- 5.933
1/8---- 9.111
mph--- 77.28
1000---11.864
1/4 ----14.176
mph----97.59

Again with the stock intake on a later date. Sept. 9, 2011: 79 degrees, 1554ft Density Altitude, 95.53% Relative Density

60ft -- 2.096
330 -- 5.926
1/8 ---9.102
mph -- 77.27
1000 --11.859
1/4 --- 14.181
mph -- 97.15

And after the intake porting, Jan 20, 2012: 71 degrees, 1168ft Density Altitude, 96.63% Relative Density

60ft --- 2.106
330 --- 5.935
1/8 --- 9.071
mph -- 78.33
1000 -- 11.792
1/4 --- 14.075
mph -- 99.28

Results explained. 1 tenth quicker, 2 mph faster. That was an awful lot of work for such a small gain lol. There could have been more meat taken off on the bulk of the intake runners and base but there was not really any meat left for making the base intake ports any "straighter". As for how the car feels, the seat of the pants swears it has more power over 5000. It's still a tpi, but the falling on its face is not as bad as it once was. The trade off? Touching the gas from a stop doesn't make the car lurch as violently as it used to. The cruise control + 1 mph button is also not as abrupt at accelerating as it once was. Its easier to launch the car since the just off idle power is a bit less. Clearly the gain up top more than made up for the loss on the low end or else it would have been slower. I am sure if I had a nice set of free flowing headers the intake port gains could have been better realized. But there you have it, a not so radical port job on a mostly stock TPI.

TTOP350

iTrader: (8)

looks like a 300 some foot DA change helped also.

Thats about what I expected.. Was your timing set the same as before?

ninetyone

iTrader: (2)

I got the idea of using runner spacers cause the best intake combo i have seen is the Stock extruded honed base and TPIS runners which are longer than stock runners. This combo made more torque down low while also making much more hp up high.

Dark Ember

I'm not so sure the DA helped much. If you look at the 2 previous times they are basically identical and there is about 400ft DA difference. But who is to say.

As for the timing I marked the distributor and set it in the same spot. However, I don't think its accurate to say anyone could pull a distributor, and restab it without possibly going off a degree or so. But I got it as close as I could. I made a few more passes at the track that I did not mention because I was tuning the timing and fuel pressure, and this post is just about the gains from an intake. The timing was at 3 degrees ATDC. The stock calibration is 0, but this is the first time the car has been timed since I owned it. I set the timing to 4 degrees BTDC, and lowered the at idle fuel pressure from 55psi down to 40psi. After these changes, later passes eventually yielded a 13.8 @ 99. It also had a brief audible detonation at 4 degrees base advance. I'm not running premium gas. The track closed before I could further test and tune. But the fuel pressure drop improved about .05 et. The timing improved .2 et and 1 mph, with detonation. But this goes beyond the scope of intake port testing doesn't it? This car still runs stupidly rich and theres still power to be gained from timing and a tune in general. But I am saving that for the last thing I do. Headers are next, along with high flow cats. Then the tune, at which point the firebird is a done project and I once more resume toying with my monte.


ninetyone, are you sure the tpis runners are longer than stock? I gotta say I'm suprised they pull on the top end the way they do if they are longer. I guess a bigger port is a much needed item on a TPI.

TTOP350

iTrader: (8)

I was asking about the timing just because if its not the same as the 1st tests, then that messes up the results. Fuel PSI and DA needs to be the same also or the results won't b accurate.
If its a factory 305-350 TPI car the base timing should B 6degs BTDC. I run about 10-12 give or take base on a untuned car lightly modded carand 48ish fuel psi. You should be running 93 at the track.

Dark Ember

This car is just a daily driver, or else I would gladly tune it for high octane gas. I believe that you want to run as low of an octane as possible for a given setup without causing detonation. The higher the octane, the less B.T.U.'s of energy, and thats what makes the power. My emissions label under the hood says base timing needs to be 0 degrees. Its a 90' 350 TPI. I definetly understand the importance of consistent timing for the sake of testing. I really think that a large reason that I saw such small gain is due to the fact that I am on the stock "log" style exhaust manifolds. Those are a major choke point for moving air through the engine.

I also forgot to bring my timeslips to my parents today, so it will be a bit longer before I scan in the slips.

TTOP350

iTrader: (8)

If you can, post a pic of the underhood lable.. I've never seen a TPI with 0degs of timing recommended, esp a 350 car. Ive only seen TBIs recommend 0degs.
On the Octane, your correct to a point. No need to over octane a motor because that kills power also. I think the HP 305-350s recommended 91 minimum...
When I used my car 4 daily driving I ran cheap stuff with base timing of 6degs until the day before Id take it to the track then It would get a load of 93 and a timing bump.

BuzzLOL

.. Yes, you may not be getting detonation with 87 octane, but that is prolly because the ECM is seriously pulling back ignition timing/power...

.. The slight BTU loss with higher octane gas is more than offset by increased HP and MPG... and with modern octane boosters, and the small amount added, there may not even be any loss of BTUs anymore...

.. The idea of adding spacers to space the runners out is becoming intriguing... IF the spacers have the ports siamesed together in pairs at both top and bottom... or even siamesed in 4's...!!! . I'll have to look and see how far the runners could be spaced out without hitting something!

305sbc

iTrader: (3)

Yep, your exhaust is putting a damper on (attenuating) any major air flow changes upstream.

The way the factory PROM is calibrated it's impossible to get the optimal timing curve by changing just the base/initial.
You can boost your initial and gain power down low, but then you get spark knock up high which negates much or all of the gain.

Re-calibrate your PROM and then you can have a good timing curve, even using the 87 octane.

The main reason that the factory engines respond so well to increased spark advance with the premium fuel is because the factory calibration is ridiculously rich in PE mode, (even without positive fuel trims being added).

When you get your AFR more in line with maximum power, the engine will want less spark advance in the 3000 RPM and up range.


I think you would be happy getting a chip burner and playing with it.

cuisinartvette

You cant make the base too big dont be afraid to dig deep.

got about the same gain no an 89 Vette porting the stock base with stock runners plenum untouched nothing else. Wasnt even that aggressive of a job (in fact it was my first ever).

So there is plenty more there dig in. Cant have too much volume on a TPI
You will gain torque everywhere, 0 loss

Those runners you can go a whoooole lot further with, take the inside (not the divider wall) wall way down and follow it around it will be easier to get to the center turn of the runner. You got some gain but still more on the table if you want it. Using a 6" carbide and cutting it down some will help you a bunch. Single, double cut doesnt matter. Dont worry about pretty it dont make it run any different. Smoothing out the carbide marks witha roll will help to an extent thats it.

Dyno Don

iTrader: (7)

completely

no new tires

sub-d