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Old 04-16-2014, 11:33 AM   #9481
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I do beleive the Midwest Series will be following the ROAR rules, as I was looking at making one or two of the events. The Byrons race in June, which is not part of the series, will be running an open engine just like the guys in Texas and Utah do.

But from what I have seen, and I do travel quit a bit and race the GT class, you really are not giving up much if anything with a good 5 port. Exception being Homestead that has a 300+ long straigt.

I'm going to take 5, 7 and 9 port engines to the Novarossi race in Houston and we'll see how it goes. My guess is the 7 port with thier 260' straight, but the 5 port may surprise me. In the past, the 9 port which is a true onroad engine just does not work as well in the infield. It was built and modified for 4wd open cars ..... really works well there.

I have raced against the ISON in LA and it was fast. Ty has the clio, from Murnan and since I use his stuff as well, know it would be a good option. I'm not sponsored by him, but purchase his stuff as it just works ......


Yes the ISON is the best overall choice, especially since your track is going by ROAR rules!
Here in houston (my home track) the 9 ports rule and have the fastest lap and qualifying records at every event this year ( i know because i have had the TQ and fastest lap at both of them and in Brownsville with a 9port!!) . The straight is 260 ft but you go into the straight at a higher speed than homestead! If your car is setup good you are full throttle immediately after the timing loop where as in Fl you go into the straight from a very sharp turn. We get the same speeds here in houston that were run in Homestead!

The class is still evolving and we as a group are figuring out how to make these cars fast!! Just look at how much quicker GT was in FL than last year!! 2013 fast lap was 19.89 and i think only 2 guys did it , 2014 that time got pounded down to 19.2 with a handfull of guys running mid 19's It was very exciting to watch Paolo and Scotty grind it out , incredible actually!


More food for thought on the port debate, in FL the faster sportsman guys were still running 54-56mph on speed and the majority of the pro guys were running 55-58 MPH Paolo and Scotty were able to crack of a few 60-61mph speeds. Some of the sportsman lap times crept into the mid 20 sec range which is also where the majority of the pro class car were ( i had engine issues but my fastest lap for the weekend was 20.01) So you have to ask yourself this question, If a restricted 5port can get within a few MPH of an unrestricted 9port then why run a 9 port? and why did no pro run modded 5ports? I asked this question myself and was told simply "9 port novarossi engines are faster all around than the 7 and especially 5 port, its that simple". when you restrict an engine(via smaller venturi) you dont lose top end you lose bottom end) , the engine will not wind up as fast with a restriction, thats just how engines work. max RPM is max RPM a restrictor will not change that, it will however slow down how long it takes to get there. SO in laymans terms a restricted 5port will not have more bottom end than a non restricted 9 port!!
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Old 04-16-2014, 11:36 AM   #9482
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the ISON is an onroad based 5 port, it does not have more torque than a 9 port, timing is what determines tq and why the myth of 5pt having more bottom end than 9 port comes from. These are words coming from the man himself , i was skeptical on this until it was explained to me in detail. I set my 9port as Paolo instructed me to do and it has more power on the bottom and clearly up top over my 5pt and 7pt. the 9port engines are just faster all the way around. Watch the vid, there is no lack of bottom end. Ask yourself why an offroad engine has so much more bottom end? it is the port timing more so than the actual port count. I ran my 9port on a very short small track at the brownsville brawl and it was still faster than the 5 and 7 port engines especially on the infield. Now what you cannot do is just throw the engine in and turn some screws , it has to be setup via gearing and clutch but once thats taken care of there is no where that a 9 port will suffer. Like i mentioned earlier these are PM's words spread to me and i think we all know his Nova knowledge is superior.
The trick to any setup is to keep the engine in its power band and "on the pipe" that is controlled by clutch,pipe selection and gearing. We can agree that more air means more power so in that sense the 9port will create more power with a wider powerband. We can also agree that how your clutch engages determines your "infield" power. In this vid Eduardo and I are running 9ports everyone else is running 5 and 7ports. Show me where i am losing any ground on the infield?!!! Its actually the opposite Eduardo (yellow cobra ) has slightly more top speed than me but my bottom end and midrange is stronger especially on exit!
https://www.youtube.com/watch?v=1Gy1...aTUHBBuDw#t=55
this is a 5port, same story the TOP 9pt is just faster all around
https://www.youtube.com/watch?v=1Gy1...TUHBBuDw#t=113

I agree that the ISON would be the better choice for anything other than an all out national event. I doubt you will see a 5port do well in Homestead and i know its not going to be fast enough here in TX at Mikes, Joliet is a smooth sweeping track so i think the 9port will be superior there too, we will see in a few weeks!!
So basically if this holds true the only benefit to lower port count would be run time? I'm having just as hard of time with this as you did Lol. So why are we running 4 ports in buggy, only for run time? Also the 5 port in which we were talking about had modified timing so really we aren't comparing the same engine.

Good discussion Marcus! This is the kind of stuff that will help everyone.
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Old 04-16-2014, 11:42 AM   #9483
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Also Andy was not running a box stock Ison 5 port engine in Calif. as I read somewhere. I'm with Marcus on this matter and will eventually get a 9 for our tracks we all race at.
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Old 04-16-2014, 12:12 PM   #9484
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So basically if this holds true the only benefit to lower port count would be run time? I'm having just as hard of time with this as you did Lol. So why are we running 4 ports in buggy, only for run time? Also the 5 port in which we were talking about had modified timing so really we aren't comparing the same engine.

Good discussion Marcus! This is the kind of stuff that will help everyone.
run time is about the only advantage and the fact that a 5 port is much easier to drive.Hence "sportsman" engine! and on that subject a person can go to a 5port and actually run more laps than he could with a 9 port simply because its easier to drive. And we all know RC racing is about "Laps per time" and not fast lap or top speed. On most tracks you have 10 turns and 1 straight, how much time can you actually make up by having 4mph faster top end? no matter how fast you go you still can only go so fast through the turn at the end of the straight. fast laptimes are made in the turns more than anything else. If your car does not have corner speed your losing valuable time.

A buggy engine has MUCH less timing and the power band is designed for grunt hence the long header/pipe and relatively low RPM powerband. And runtime of course. One of the reasons that if you run a #4 plug in an onroad engine you will not make 5 laps before it spits the plug out!! ( dont try it!!)

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Originally Posted by Pit-racer View Post
Also Andy was not running a box stock Ison 5 port engine in Calif. as I read somewhere. I'm with Marcus on this matter and will eventually get a 9 for our tracks we all race at.
Well, there ya have it!
I have a modded 5port that is a screamer but runtime is so low i can barely make 6min!! Even so it doesnt have more bottom end than my stock 9 port but it does have a stronger midrange. Once you start modifying engines the powerband shrinks, thats not necessarily a bad thing but thats what happens.
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Old 04-16-2014, 12:41 PM   #9485
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Yes the ISON is the best overall choice, especially since your track is going by ROAR rules!
Here in houston (my home track) the 9 ports rule and have the fastest lap and qualifying records at every event this year ( i know because i have had the TQ and fastest lap at both of them and in Brownsville with a 9port!!) . The straight is 260 ft but you go into the straight at a higher speed than homestead! If your car is setup good you are full throttle immediately after the timing loop where as in Fl you go into the straight from a very sharp turn. We get the same speeds here in houston that were run in Homestead!

The class is still evolving and we as a group are figuring out how to make these cars fast!! Just look at how much quicker GT was in FL than last year!! 2013 fast lap was 19.89 and i think only 2 guys did it , 2014 that time got pounded down to 19.2 with a handfull of guys running mid 19's It was very exciting to watch Paolo and Scotty grind it out , incredible actually!


More food for thought on the port debate, in FL the faster sportsman guys were still running 54-56mph on speed and the majority of the pro guys were running 55-58 MPH Paolo and Scotty were able to crack of a few 60-61mph speeds. Some of the sportsman lap times crept into the mid 20 sec range which is also where the majority of the pro class car were ( i had engine issues but my fastest lap for the weekend was 20.01) So you have to ask yourself this question, If a restricted 5port can get within a few MPH of an unrestricted 9port then why run a 9 port? and why did no pro run modded 5ports? I asked this question myself and was told simply "9 port novarossi engines are faster all around than the 7 and especially 5 port, its that simple". when you restrict an engine(via smaller venturi) you dont lose top end you lose bottom end) , the engine will not wind up as fast with a restriction, thats just how engines work. max RPM is max RPM a restrictor will not change that, it will however slow down how long it takes to get there. SO in laymans terms a restricted 5port will not have more bottom end than a non restricted 9 port!!
While I don't know much about on road racing I do know a little about Nitro engines and internal combustion engines in general. I would have to disagree with the statement in red. When you use a smaller venturi you increase air speed at lower rpms which gives you more torque. with a smaller venturi you reach maximum air flow (which is 650 feet per second) much sooner thus restricting power output at higher rpms.

Maybe our 2 stroke nitro engines are different than a car engine but this is something i have always believed for any internal combustion engine.

here is a quick link about it..

http://gglotus.org/ggtech/hp-theory/hptheory.htm
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Old 04-16-2014, 01:08 PM   #9486
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While I don't know much about on road racing I do know a little about Nitro engines and internal combustion engines in general. I would have to disagree with the state in red. When you use a smaller venturi you increase air speed at lower rpms which gives you more torque. with a smaller venturi you reach maximum air flow (which is 650 feet per second) much sooner thus restricting power output at higher rpms.

Maybe are 2 stroke nitro engines are different than a car engine but this is something i have always believed for any internal combustion engine.

here is a quick link about it..

http://gglotus.org/ggtech/hp-theory/hptheory.htm

Yes 2 stroke engines are different because they have a distinct power band that is not controlled by a cam shaft /valves. A restrictor restricts power across the board. Its easy to test simply swap them out and test. I put a 6mm restrictor on my kids car just to tame it down on the infield and it works. you cant create more airflow than whats available. At any particualar RPM the engine can only suck in so much air as RPM's increase so does that number. For instance (hypothetical numbers ) if at 20k RPMs your engine sucks in 100CFM of air and at 40k it sucks 200 CFM with a 8mm venturi how is putting a 6mm restrictor going to make the engine suck in more air (which would have to equal more power)? the only way thats possible is in a turbocharged situation where air is being fed into the engine and in that case then yes i can see a smaller venturi creating faster air and restricting top end because pressure and flow is being forced past the venturi and into the engine.That theory is also assuming that you reach max air flow, these engines turn 30k+ RPMS, if we were only playing with 8k RPM's things would be different.

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Old 04-16-2014, 01:28 PM   #9487
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I guess i didn't make my self clear. You are absolutely correct that a larger restrictor will make more horsepower and that a smaller restrictor will decrease air flow.

But what happens is, the speed of the air coming into the engine increases faster at lower rpms(with a smaller restricotr vs a larger restrictor). Thus changing the power band, providing power SOONER (lower in the rpm) than a larger restrictor. This gives the feeling of more low end power because the engine will produce power faster. (not to be confused with producing more power)


With a larger restrictor the engine will most definitely produce more power.. it just takes more RPM to increase the air speed thus the engine takes a little longer to produce the power. This can feel like less torque.

I think it's all about gearing and keeping the engine in the "sweet" spot and "on the pipe"
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Old 04-16-2014, 02:26 PM   #9488
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Man I just got off the Pipe .... now you're telling me to get back on it.
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Old 04-16-2014, 02:39 PM   #9489
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I guess i didn't make my self clear. You are absolutely correct that a larger restrictor will make more horsepower and that a smaller restrictor will decrease air flow.

But what happens is, the speed of the air coming into the engine increases faster at lower rpms(with a smaller restricotr vs a larger restrictor). Thus changing the power band, providing power SOONER (lower in the rpm) than a larger restrictor. This gives the feeling of more low end power because the engine will produce power faster. (not to be confused with producing more power)


With a larger restrictor the engine will most definitely produce more power.. it just takes more RPM to increase the air speed thus the engine takes a little longer to produce the power. This can feel like less torque.

I think it's all about gearing and keeping the engine in the "sweet" spot and "on the pipe"

Yes, you are correct! except for the port volume, A 9 port will fill that volume much quicker than a 5 port which goes back to the fact that a 9 port will make more low end power than a 5 port!! My 9 port is stronger across the board and i use clutch/pipe/gearing to keep it on the pipe!

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Old 04-16-2014, 02:39 PM   #9490
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Man I just got off the Pipe .... now you're telling me to get back on it.

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Old 04-16-2014, 02:59 PM   #9491
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Lol, no comment +2
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Old 04-16-2014, 03:06 PM   #9492
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Yes the ISON is the best overall choice, especially since your track is going by ROAR rules!
Here in houston (my home track) the 9 ports rule and have the fastest lap and qualifying records at every event this year ( i know because i have had the TQ and fastest lap at both of them and in Brownsville with a 9port!!) . The straight is 260 ft but you go into the straight at a higher speed than homestead! If your car is setup good you are full throttle immediately after the timing loop where as in Fl you go into the straight from a very sharp turn. We get the same speeds here in houston that were run in Homestead!

The class is still evolving and we as a group are figuring out how to make these cars fast!! Just look at how much quicker GT was in FL than last year!! 2013 fast lap was 19.89 and i think only 2 guys did it , 2014 that time got pounded down to 19.2 with a handfull of guys running mid 19's It was very exciting to watch Paolo and Scotty grind it out , incredible actually!


More food for thought on the port debate, in FL the faster sportsman guys were still running 54-56mph on speed and the majority of the pro guys were running 55-58 MPH Paolo and Scotty were able to crack of a few 60-61mph speeds. Some of the sportsman lap times crept into the mid 20 sec range which is also where the majority of the pro class car were ( i had engine issues but my fastest lap for the weekend was 20.01) So you have to ask yourself this question, If a restricted 5port can get within a few MPH of an unrestricted 9port then why run a 9 port? and why did no pro run modded 5ports? I asked this question myself and was told simply "9 port novarossi engines are faster all around than the 7 and especially 5 port, its that simple". when you restrict an engine(via smaller venturi) you dont lose top end you lose bottom end) , the engine will not wind up as fast with a restriction, thats just how engines work. max RPM is max RPM a restrictor will not change that, it will however slow down how long it takes to get there. SO in laymans terms a restricted 5port will not have more bottom end than a non restricted 9 port!!
Not trying to feed an argument but how much more effective will your 9 port be at one of our local tracks? We have a great love for the GT in Utah but we don't have the monster tracks many of you enjoy. Although this video is a few years old we raced weekly at this track up until this year when it closed. Not many 9 ports here. We do have another track we race at that is bigger but this track made ya learn to really drive your car. It was one more day a week we got to run our GTs.

https://www.youtube.com/watch?v=DCSjEIB88Hk
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Old 04-16-2014, 03:22 PM   #9493
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Yes, you are correct! except for the port volume, A 9 port will fill that volume much quicker than a 5 port which goes back to the fact that a 9 port will make more low end power than a 5 port!! My 9 port is stronger across the board and i use clutch/pipe/gearing to keep it on the pipe!

Yes and no. The more/larger ports you have the less vacuum you produce at lower rpm. This decreases airflow at lower rpm. The more ports you have the more rpm you have to turn to create the same amount of vacuum.

If you compare the same vacuum numbers between a 9 poet and 5 port the 9 port will be making more power, it just takes more rpm to get there.

I am not advocating that less ports is superior, but they do make power fast than more ports. I have no doubt that a properly clutched/geared 9 port is superior in power to a 5 port.

But on a dyno side by side the 5 port will make power sooner than the 9 port.
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Old 04-16-2014, 03:28 PM   #9494
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Not trying to feed an argument but how much more effective will your 9 port be at one of our local tracks? We have a great love for the GT in Utah but we don't have the monster tracks many of you enjoy. Although this video is a few years old we raced weekly at this track up until this year when it closed. Not many 9 ports here. We do have another track we race at that is bigger but this track made ya learn to really drive your car. It was one more day a week we got to run our GTs.

https://www.youtube.com/watch?v=DCSjEIB88Hk
I tqd on this track with a 9 port!!
https://www.youtube.com/watch?v=PkBtJY0PdE8

As i keep saying it does not matter, the 9 port makes more power, on that track i would simply gear down and change shift points! worst case scenario i can change to a longer header but I am not taking my 9 port out for anything

Dont worry about feeding an argument, i dont think we area arguing just discussing. If you have a question please let er rip!!
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Old 04-16-2014, 03:45 PM   #9495
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Yes and no. The more/larger ports you have the less vacuum you produce at lower rpm. This decreases airflow at lower rpm. The more ports you have the more rpm you have to turn to create the same amount of vacuum.

If you compare the same vacuum numbers between a 9 poet and 5 port the 9 port will be making more power, it just takes more rpm to get there.

I am not advocating that less ports is superior, but they do make power fast than more ports. I have no doubt that a properly clutched/geared 9 port is superior in power to a 5 port.

But on a dyno side by side the 5 port will make power sooner than the 9 port.

Ok, so lets get some variables pointed out before we get all crossed up with information

My comparison is for a 7mm restricted 5 port (ROAR legal)
and un restricted 8.5mm 9 port.

now something that i would like to point out is that you get no vacuum once the throttle is wide open you get ambient pressure which is 14.7 ( ie stoichemetric)

I am also not arguing your point IF there is no restriction a 5port may create more power but at a level where it does no good at least not for on road GT racing. Going to the extreme of our sport 1/8 open, those guys clutch and gear so that the engine is in its powerband the entire time. If you take a modded un restricted 5 port and gear it so it can even get close to the 9 port on a heavy GT car its not going to go anywhere, 1 st gear may be ok but its going to suffer on the straight. Case and point the REDS M7 and WC are both 7 port engines but they have HUGE ports. i was sponsored by them last year and going from REDS to TOP, the first thing i notice was that the REDS engines turned really high rpms and had astounding mid and top end . Where as the TOP has a much smoother powerband and not quite as violent as the REDS on the bottom.

You are not wrong on anything you are saying, I am just trying to put it into GT perspective! a 5port is not Torquey by any means at least not enough to out perform a 9 port with the same variables.
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