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hpi rs4 3 twin engine build

Old 04-08-2012, 10:03 PM
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jscraper
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Default hpi rs4 3 twin engine build

ive started working on my twin engine build. does anyone know of anyone else that has attempted or completed this build before?

here are some pics of my progress.
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Old 04-10-2012, 06:50 AM
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keinreis
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Default RE: hpi rs4 3 twin engine build

Looks like a cool project. I think your biggest challenge will be synchronizing the carbs. I would think they would have to be dead on IMO.
Old 04-10-2012, 09:43 AM
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Explicit_Spade
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Default RE: hpi rs4 3 twin engine build

Won't the engines be battling themselves trying to turn the drivetrain different ways, or was something internally flipped to make them work together?
Old 04-10-2012, 11:37 AM
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keinreis
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Default RE: hpi rs4 3 twin engine build


ORIGINAL: Explicit_Spade

Won't the engines be battling themselves trying to turn the drivetrain different ways, or was something internally flipped to make them work together?
I had to think about this one for a min, but you are right. motors would have to spin oposing direction.

Old 04-10-2012, 12:03 PM
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fdjizm
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Default RE: hpi rs4 3 twin engine build

No they don't they will be spinning the spur gear in the same direction.
You have them setup fine, both engines spin clockwise from the rear, spinning the spur in the same direction.
Old 04-10-2012, 12:31 PM
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jscraper
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Default RE: hpi rs4 3 twin engine build

thanks for drawing the picture. thats what i was going to do. yep this setup will work. i figured out how to run the linkage also. ill post pics tonight. im also going with the nitro star t3.0 engines. got the first one in yesterday. waitin on the other.
Old 04-10-2012, 01:04 PM
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keinreis
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Default RE: hpi rs4 3 twin engine build

yes I was thinking about this again on my drive home from work, and as the drawing shows, the motor setup is right. Brain fart on my end. Synchronizing the carbs will still be a challenge. I have faith tho. Challenge #2 will be routing the exhaust for the new motor. I can't wait to see a video of this one running around!
Old 04-10-2012, 03:15 PM
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fdjizm
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Default RE: hpi rs4 3 twin engine build

I say tune one motor at a time even setting the carb the same on both won't be equal.
Old 04-11-2012, 09:51 AM
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tomst-maxx
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Default RE: hpi rs4 3 twin engine build

If both engines are brand new syncing the carbs shouldnt be impossible. I think the big challenge is the trottle linkage, getting an equal pull at both carbs at the same time. I think this is going to be one hell of a nice ride once you get it going.
Old 04-11-2012, 12:43 PM
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jscraper
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Default RE: hpi rs4 3 twin engine build

sorry for not posting those pics. got off work super late lastnight. yes, both engines will be new. yah its going to be legit!!!!!! i basicly have everything figured out. just waiting on parts now. the next thing im worried about is traction. what wheel/ tire combos do you think would give me good traction?
Old 04-11-2012, 05:34 PM
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tomst-maxx
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Default RE: hpi rs4 3 twin engine build

wheels and tires depend on what you plan on doing with the car. Are you going to go for speed run? Just as show? or a basher type?
Old 04-11-2012, 05:39 PM
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Default RE: hpi rs4 3 twin engine build

speed/ bashing. lol
Old 04-11-2012, 06:44 PM
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nastyboys727
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Default RE: hpi rs4 3 twin engine build

i just did a ofna gtp2 with twin lrp .30's
best thing to do would be to tune them one at a time
and the linkege its not hard to do just think it out i used two rods with the ball cup end on them one short and a long one that will reach out to the servo best to be a bit longer you can always cut it and to hold them together i used one of those dubro rings with the setscrew in it to lock them
together around the center of the carbs so you wont have any binding probs. thats all easy its your gearing that you gotta get rite if not
like i see you have about scock gearing your gonna have boat loads of off line power like tire scredding power but your topend is gonna kinda be about the same thats where i was till i went bigger gears on my bell's
Old 04-11-2012, 06:45 PM
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nastyboys727
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Default RE: hpi rs4 3 twin engine build

and run braces from diff to tranny to diff
Old 04-11-2012, 09:29 PM
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Default RE: hpi rs4 3 twin engine build

thats the best topend gearing i could find. im running 17/23 pinion and 43/39 spur gears. is there any better topend gearing out there? that i couldn't find.

and i was thinking about swaping the diff gears with the evo+ gears gives it alittle more top end.
Old 04-11-2012, 09:39 PM
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Default RE: hpi rs4 3 twin engine build


ORIGINAL: jscraper

thats the best topend gearing i could find. im running 17/23 pinion and 43/39 spur gears. is there any better topend gearing out there? that i couldn't find.

and i was thinking about swaping the diff gears with the evo+ gears gives it alittle more top end.
If you use the Losi LST threaded clutch bell you can get threaded pinions from RC Monster up to 24T for your first gear and 30T for for your second gear. I would think that 24/30 should boost your top end nicely!
Old 04-11-2012, 10:43 PM
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jscraper
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Default RE: hpi rs4 3 twin engine build

thats awesome!!!!!! im going to look into that. thanks
Old 04-11-2012, 11:01 PM
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Default RE: hpi rs4 3 twin engine build

to use that clutch bell do i need to change anything else? like the pilot shaft, bearings, clutches, flywheel?
Old 04-12-2012, 09:19 AM
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Default RE: hpi rs4 3 twin engine build

everyone is digging into these dual engine rigs... cool.

i was to do it i would do a dual .28 in a 1/10 i already have a force .28 laying around. 2.7hp X 2= broken drive train
Old 04-12-2012, 10:30 AM
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Default RE: hpi rs4 3 twin engine build


ORIGINAL: tomst-maxx

If both engines are brand new syncing the carbs shouldnt be impossible. I think the big challenge is the trottle linkage, getting an equal pull at both carbs at the same time. I think this is going to be one hell of a nice ride once you get it going.
You don't have to sync them. Each carb is on a separate engine. You only have to sync when there are multiple cars on the same multiple cylinder engine. He can just do them one at a time. No reason to have both engines running at the same time when you're tuning.
Old 04-12-2012, 02:07 PM
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Default RE: hpi rs4 3 twin engine build

ORIGINAL: jscraper

to use that clutch bell do i need to change anything else? like the pilot shaft, bearings, clutches, flywheel?
I actually don't remember if you need to change anything or not. I was using both the RS4 and LST bells on my Kyosho Inferno GT I don't remember if spacing was different or not. They should be pretty close though, shims may be all you need I do remember needing 3 5x10 bearings with the LST bell. And if you need any extra length this should get you there http://www3.towerhobbies.com/cgi-bin...?&I=LXNT03&P=M
Old 04-12-2012, 04:25 PM
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mike31
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Default RE: hpi rs4 3 twin engine build

Think about it. Engines mounted on either side of a driven gear need to turn in the same direction. One engine (left side) drives off the up rotation the other (right side) drives off the down rotation. They will not fight each other but will turn the driven gear easily.
Old 04-12-2012, 04:29 PM
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Default RE: hpi rs4 3 twin engine build

Agree!!!
Old 04-15-2012, 06:08 AM
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Default RE: hpi rs4 3 twin engine build

you would need to go with 2 1/8 clutch set ups from flywheel out coz the lst bells are bigger around  and get the lst bells coz the lst2 bells have fixed gears you want the screw on typeand with the hpi 2 speed the gears are kinda close so you gotta put the first speed one on backwards so thay can be close together like the hpi setup is
Old 04-15-2012, 06:47 AM
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Default RE: hpi rs4 3 twin engine build

JSCRAPER, I started building one a few years ago and decided on an 1/8 scale version since I wanted to run a large motor. Didnt want to come up short on power at the end. Youre going to come across some challenges while building it but just work thru them and you should be alright. Honestly, I built mines without many people knowing to keep foreign influences from hampering me and thats the biggest challenge. I say go for it and build it. If you need any info or advice, please dont hesitate to shoot me a PM.

BTW, your best bet is to go with rear exhaust motors. Here's a vid of mines when it was done.

http://www.youtube.com/watch?v=xgTbH...feature=relmfu

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