R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro On-Road > Onroad Nitro Engine Zone

Thread Tools Search this Thread
Old 11-20-2009, 04:36 AM   #1
Tech Elite
J.Gonzalez's Avatar
Join Date: Nov 2002
Location: connecticut
Posts: 2,409
Trader Rating: 16 (100%+)
Default Power versus runtime

Hypothetical scenario....medium sized track with super high bite and must wind out first gear to optimize laptime

High output 9 port engine (non tuned say 35 plus with 2052) running on 25% fuel provides fast lap time however regardless of tuning unable to make runtime for 5 minutes and must pit in qualy

Only way to make time is to detune engine with (35 plus with 2015) pipe and running 16% fuel. Laps times drop about .2-.3 sec but now able to make 5 minutes. This setup is marginal as motor has to be run on the limit to make time and finding that slightly higher elevation along with low nitro and borderline lean leads to short bearing and engine life.

7 port engine (R1wcs 2052) with power pipe able to make run time on 25% fuel but yields slower lap time at slightly less as detuned 9 port engine. Motor seems to lack top end on straight and short chutes but has good performance off corner.

In this hypothetical scenario would a modified/tuned 7 port engine be worth investing in a compromise between between both scenarios listed above.

I am trying to get some addtl info before I make a 500$ experiment ha!

Last edited by J.Gonzalez; 11-20-2009 at 04:53 AM.
J.Gonzalez is offline   Reply With Quote
Old 11-20-2009, 05:32 AM   #2
Tech Champion
Roelof's Avatar
Join Date: Aug 2007
Location: Holland
Posts: 5,358
Send a message via ICQ to Roelof

You have to forget the idea that more ports will give more power, it is more a commercial statement than a real technical/performance statement. In a 2-stroke engine timings and dimensions are the most important factors for performance, not the amount of ports.
Beside that, matching materials for piston and sleeve as also the precission of which they are made will determ a huge part for the performance.

3-port engines can run as fast as 9 port engines, I think the .12 touring cars did show that already for years.

Regarding power and consuming, that is for the most part an exhaust thing. Just get a 2013 exhaust and you can reach 5:30 with the 35+ engine. Getting more time is not only a power issue, it is how you setup the complete system:
- exhaust (type)
- manifold (conical or not and length)
- backpressure (there is a lot to play with)
- airfilter/insert
- type of carb needle (yes, there are other types)

And yes, it is possible to get more runtime after tuning the engine. A better flow and different resonances inside the engine can create less loss of the mixture.
Speed is only fiction but a 130+km/h MRS4 is for real.
Roelof is offline   Reply With Quote
Old 11-20-2009, 02:44 PM   #3
Tech Master
Join Date: Jan 2004
Posts: 1,218
Trader Rating: 13 (100%+)

You basically answered your own question

If your engine makes 5 minutes and a lap, (you might cross at 4:59, and pitting on fumes sucks) then you are basically good. Time is always what you look at when trying to make a decision like this. No engine likes to be at the rpm limit like how we constantly bang the 21's in 8th scale but it's how it is and you just have to replace the bearings. Off corner zip can be had from the clutch.

On the flip side to that, I did see Mike Swauger pit at I believe 4 minutes flat at the nationals and switch tires halfway through the hour and was ahead by a lap at the switch, and then ahead by a lap at the end. Everyone else was pitting at 5 and nobody else switched tires except his pit man is spectacular so he can do that. Fuel and 4 tires in 16 seconds. Mike did pit at 4:?? in the qualifiers and it wasn't good for TQ although his pace before the pit was always low.
Support those that support us

http://ActivRC.com http://TeamPowersUSA.net
Brian Bosley is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

All times are GMT -7. It is currently 07:59 AM.

Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net

SEO by vBSEO 3.5.0