DYNO of Intake manifolds:1st gen vs 2nd gen

[naprotejay]

Did some experiments on a Dynojet @ sea-level. Temp was mid 70's, engine had 223,440 miles, new spark plugs/wires, 87 octane, and the mods (minus the 2nd gen DC) listed in my sig.

Basically i wanted to compare the 1st gen and 2nd gen upper intake manifold - or Dynamic Chamber, DC for short. The 2nd gen DC is 1" taller, giving it a correspondingly larger volume than the 1st gen DC. I expected it to produce gains comparable to the header, but.... NEVER trust your butt dyno

First i wanted to get some baselines on the Dynojet with the stock 1st gen DC:

1st run - 16 degree timing:

---- 113.1 hp/108.0 ftlbs ----
nice, smooth power from 3000rpm-4200; then VERY choppy untill 6400-7000, where it went smooth again


2nd run - 14 degree timing:

---- 115 hp/107.4 ftlbs ----
overall good-looking run

3rd run - 11 degree timing:

---- 113 hp/103.8 ftlbs ----

Next, i put it back to ~14 degrees timing, and then tuned the RX7 some but didn't really do any better than with the setting i went in with. So... i put the stock VAF on.

9th run - stock VAF(no filter):

---- 114.7 hp/108.9 ftlbs ----
virtually no loss in hp compared to the RX7 VAF but nearly 2ftlbs better torque - and the engine was thoroughly heat-soaked by then! the little difference in peak hp between the 2 VAF's was especially a surprise.

Next i let the engine cool so as to be able to put on a *modified* 2nd gen DC. Besides making the stock throttle body fit, the experimental modification involved removing the divider/ridge that separates the high rpm chamber from the main chamber. This divider is present in both DC's. A friend cut ~1" of it away using a rotary file.

Modified 2nd gen DC results:

10th run - with stock VAF(no filter):

---- 112.9 hp/107.2 ftlbs ----
surprise surprise! less hp and torque than the stock DC! (with the stock VAF....)
the air/fuel readings showed it running richer.....
however the RX7 VAF improved things

12th run - w/RX7 VAF(no filter):

---- 114.8 hp/108.5 ftlbs ----
good hp and nice torque

did a little tuning of the RX7 VAF with only minor changes.

next we made some cam changes with adjustable cam gears.

15th run - advanced intake cam 2 degrees:

---- 116 hp/108.5 ftlbs ----

16th run - retarded exhaust cam 1 degree with intake cam still advanced:

---- 115 hp/108.9 ftlbs ----

17th run - exhaust cam back to stock, intake cam retarded 2 degrees:

---- 113.8 hp/106.2 ftlbs ----

18th run - intake cam retarded 4 degrees:

---- 116.1 hp/108.7 ftlbs ----
strong hp and torque

19th final run - intake cam advanced 4 degrees:

---- 116 hp/108.5 ftlbs ----
again nice hp and torque

gotta go for now, i'll summarize some things later

[Tweeaks]

what about trying to see what the 1st gen mani does with that ridge cut out also? I've seen a write up on it somewhere. They claimed to have gains, but I have never seen any dyno on it...I was thinking about cutting out the ridges in my mani when i re-build, but am not sure if I really want to risk it because someone said it "felt" stronger, know what I mean?

[Gen1GT]

Why didn't you use 92+ octane fuel? Ignition timing is limited to 14 degrees with 87. You could have gone as high as 18, and probably would have had 119hp up there too.

Did you use the stock airbox with the RX7 VAF? I can't picture it making a difference in that case. Get a pod filter and do some more tuning.

Great work though, it's nice to see more research on the same motor. Looks like my cam gears are going to be a sooner than later purchase for me.

I'd like to see some of your dyno charts for cam timing too.

[naprotejay]

https://www.angelfire.com/extreme3/323/intakemanifold.html

i'd be interested in seeing a dyno of a modified 1st gen DC as well. however, i've just got too much other stuff going on to do it....

some other dyno-related notes:

while on the dyno, i swapped in a Escort GT ECU for the stock one - it made no difference The Escort DOHC comes with a BP09 ECU, while the Pro DOHC comes with a BP10. i had hoped maybe the BP09 was possibly tuned a little better at high rpm....

as far as the manifold differences, the stock vaf/ecu appears to be very well-matched for the stock DC with the bolt-on's, seeing as how that combo really made the best overall power of the *stock DC* runs - at least for my setup. an RX7 VAF appears unnecessary. removing the stock plumbing results in the power gains. in fact, i would be inclined to try tuning the stock VAF and see if there's some power to be had...

the modified 2nd gen DC didn't like the stock VAF. it REALLY suffered at high rpm.... like i said the air/fuel went richer compared to the stock DC/VAF.
however - interestingly - the RX7 VAF made a big difference.
When the RX7 VAF was tuned at the same setting, the 2nd gen DC made almost 2 ftlbs and ~1hp more than the comparable run with the stock DC.....

definitely nothing dramatic, but it is interesting to note tendency's. simply put, when using the *RX7 VAF*, the 2nd gen DC tended to produce more power at a lower rpm than the stock DC. this happened at VICS switch as well. it tended to start making more power sooner than the stock DC. the torque band is somewhat flatter.

as far as removing the ridge, it didn't *seem* to really do anything, BUT it doesn't appear to hurt either....

down the road if my plans work out and i'm making more na power, i think there will be a more dramatic difference between the 2 DC's....at this point, i'm sticking with the modified 2nd gen DC/RX7 VAF.

bty if anyone's interested; i have a stock DC, and a spare unmodified 2nd gen DC fitted with a 1st gen TB available - email or pm me.

[naprotejay]

Why didn't you use 92+ octane fuel? Ignition timing is limited to 14 degrees with 87. You could have gone as high as 18, and probably would have had 119hp up there too.

Did you use the stock airbox with the RX7 VAF? I can't picture it making a difference in that case. Get a pod filter and do some more tuning.

Great work though, it's nice to see more research on the same motor. Looks like my cam gears are going to be a sooner than later purchase for me.

I'd like to see some of your dyno charts for cam timing too.

good question - i guess i've just never thought to use 92 octane and advance the timing even more.....

*none* of the runs were made with the stock airbox/plumbing. i'd like to see someone else test a stock VAF vs a tuned RX7 VAF - both with the same setup; be it a pod/cone filter, no filter, etc.. a true apples to apples comparison. that would help confirm whether or not the RX7 VAF produces power over the stock VAF with the stock DC. perhaps i just didn't try enough tuning of the RX7 VAF...

no scanner, but the dyno charts may eventually be posted....

[Gro Harlem]

damn man, you sure do a lot of dyno testing of all this stuff. I remember your old posts when you were bolting your headers and adding other stuff.

BTW: for sake of dyno-result gathering. My car w/stock vaf & intake, cone filter, stock exhaust manifold & downpipe, free-flow cat, 2.25" exhaust w/2.25" chambered muffler pulled 109.1 hp and 106 torque (forgot the rpms). This was a couple of years ago when i last dyno'ed it.

[MazdaRacer]

Jason is definetely our resident dyno man! I have been tuning on my suspension for so long now, i've forgotten about the engine....

Thanks Jay!

[naprotejay]

i guess i'm hooked on dynos it is expensive though, $320 for 2 hrs with air/fuel!! but its the only decent way of getting an idea of what does what.

i think there's good potential for a nice na Pro BP. i've seen plenty of Miata results, but nobody has really been doing anything with the Pro, and it has benefits of: less drivetrain losses, nice VICS manifold with long 'torque producing' runners, different exhaust configuration, no OBDII, no EGR valve, etc. and its flat out fun to drive to top it off!
so i just am trying to gather some data.

i hope Gen1GT and 91ProtegeLX are able to do what they are planning for na power. that'll be at least 3 pro's finding out the na performance potential with somewhat different paths...

[naprotejay]

and miatas don't have VICS?

what's wrong with having an EGR valve?

99-00 do, as does the new Mazdaspeed turbo Miata(uses same as 99-00)
any Miata owner other than 99-00 just has more work to do if they want the VICS manifold.
our VICS is a different design - not sure which is better; and we have 2 different factory designed DC's to choose from....

no EGR valve just makes for less complications and less crud in the intake system - both 2nd gen DC's i've gotten had a black buildup of EGR; the stock manifold was much much cleaner.

[1ofdfew323]

i havent been on a dyno but im planning on doing it...anyhow here's a question for u dyno peeps. Do i (customer) tune my own car at the dyno or the tech will do that for me? just wondering...

[Gen1GT]

i havent been on a dyno but im planning on doing it...anyhow here's a question for u dyno peeps. Do i (customer) tune my own car at the dyno or the tech will do that for me? just wondering...

Either. Some places might charge you extra if they're doing the work, but my technician doesn't. We both tune the car while it's set up. I'm lucky, because my guy has pretty good dyno prices(his work is good, yet expensive, although worth it), and he's flexible with time. If we take 1 1/2 hours, he'll still only charge me for 1.

It also depends on what you want tuned.

[1ofdfew323]

Either. Some places might charge you extra if they're doing the work, but my technician doesn't. We both tune the car while it's set up. I'm lucky, because my guy has pretty good dyno prices(his work is good, yet expensive, although worth it), and he's flexible with time. If we take 1 1/2 hours, he'll still only charge me for 1.

It also depends on what you want tuned.

i just want to get rid of the hesitation and vibration... ima have to find me a dyno shop where they can tune my ****. thx!

[bruce95fmla]

It's about time this surfaced.

[srad2drag]

This was a very good thread.My 1996 Escort GT. made 119.31 hp and 110 tq.N/A when I installed my gude racing package it made 138 hp and 118 tq at the wheels.Believe it or not I made the most power with 87 octane fuel.going back to the dyno with 93 and increasing timmine made me lose 2 hp. Go figure.

[naprotejay]

This was a very good thread.My 1996 Escort GT. made 119.31 hp and 110 tq.N/A when I installed my gude racing package it made 138 hp and 118 tq at the wheels......

i assume your 96 is an OBDII engine with MAF sensor - in other words a 2nd gen Protege engine??? Do you have the charts posted somewhere? i've never seen a 2nd gen BP chart....

Also, that was with the stock ecu as well?? 138whp with the stock ecu?!