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All Forums >> RC Cars, Buggies, Trucks, Tanks and more >> HPI Racing >> HPI On-Road >> Need some bottom end snap
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Need some bottom end snap - 6/12/2007 4:57:23 PM   
almtx3



Posts: 266
Joined: 1/12/2007
From: Miami, FL, USA
Status: offline 		Did a bit of searcing but couldnt find a clear answer. Got the RS4 3 18ss going to the track more often and Im looking for a bit more bottom end snap. From a dead stop or slow start I hit the throttle and there is not much go. I have the HPI gearing chart (not much to choose from) but I want to hear from someone thats tried a different gearing combo that gives a faster take off and decent top end. Im running the stock gearing right now along with the the stock 18ss engine.

Currently running = Spur: 1st gear 47 - 2nd gear 43
Pinion: 1st gear 19 - 2nd gear 23
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RE: Need some bottom end snap - 6/12/2007 5:54:11 PM   
hpi apollo



Posts: 2639
Joined: 5/13/2006
From: Georgetown, KY, USA
Status: offline 		with the right clutch and tune that engine will have more than enough power to completely spin the wheels down low so something is wrong there, i was spinning my wheels with the 43/39 spurs


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RE: Need some bottom end snap - 6/13/2007 3:46:52 PM   
almtx3



Posts: 266
Joined: 1/12/2007
From: Miami, FL, USA
Status: offline 		Powers good apollo, Im running the car at my local track so Im using foam tires. Cars got great grip so no complaints there. I must admit Im the only HPI out there running against Mugens, Serpents and Xray NT1's! Yeah talk about the underdog. I cant compare my engine to those $300-$400 monster .12's. Most guys are running RB's and Ninjas. Those engines have some serious snap! I just finished working on my buddies NT1 with a .12 ninja and that thing is a bullet. Granted I cant compare my HPI to his car and engine but what I was just looking for was maybe a bit more bottom end out of my car. Im sure you can help me out here and I look forward to your suggestions. I used to run with these guys back in the day when I had a Serpent Impact with a .12 Novarossi Michael Salven edition so Im pretty familiar with tuning, set up and actual track racing. Ive since sold the serpent and got out of the serious 1/10th racing scene. A wife, mortgage and a beautiful baby boy is the main reason for my choice with the HPI. Im on a budget now and its an affortable alternative to the high end cars. I can just go out to the track on open practice and bash around with the big boys, so im looking for every possible ounce I can squeeze out of my HPI without breaking the bank and keeping the wife happy! The cars got a rocking tune, believe me, my HPI showed some serious heart out there against those cars and most of the guys out there are pretty impressed with the cars performance. I'm just looking for some different gearing options to make the car a bit more aggressive out the hole. Since there are no other HPI's out at the track I have no one to share set-ups with and get feedback on what works and what doesnt so thats why Im here. It is what is is and I know an R40 would be ideal out there but Im just looking to have some fun and my RS4 3ss is a blast! Look forward to your suggestions...thanks for chiming in.

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RE: Need some bottom end snap - 6/13/2007 4:08:47 PM   
almtx3



Posts: 266
Joined: 1/12/2007
From: Miami, FL, USA
Status: offline
quote:

ORIGINAL: hpi apollo
i was spinning my wheels with the 43/39 spurs


I noticed you went lower than what the HPI gear chart recommends. I also read somewhere you had to modify the chassis a bit to make the gears fit. Dont want to do that, so how much of a difference will I feel if I go down to the recommended 45/41 spur combo. Your opinion - Will it make any difference at all?

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RE: Need some bottom end snap - 6/13/2007 5:12:33 PM   
Nitro212


 

Posts: 275
Joined: 9/11/2006
From: New York, NY, USA
Status: offline 		yeah, for 43/39 you will need to grind like 2 mm of the chassis ( engine mount holes ) and grind the gear box as well, so the flywheel wont touch it and have space..

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RE: Need some bottom end snap - 6/13/2007 5:27:25 PM   
almtx3



Posts: 266
Joined: 1/12/2007
From: Miami, FL, USA
Status: offline
quote:

ORIGINAL: Nitro212

yeah, for 43/39 you will need to grind like 2 mm of the chassis ( engine mount holes ) and grind the gear box as well, so the flywheel wont touch it and have space..


Ouch! Dont know if I wanna go there...thanks for the tip though. I really want to know if going to the 45/41 will make a difference. Any other tips will be appreciated. Keep them coming! Thanks.

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RE: Need some bottom end snap - 6/13/2007 5:33:00 PM   
hpi apollo



Posts: 2639
Joined: 5/13/2006
From: Georgetown, KY, USA
Status: offline 		from the stock 47/43 (if i remember right) to the 43-39 was a noticable difference in speed, also aided in traction control a tad, the only grinding was about 2mm to the side, very easy job to do, hard to screw up but i didnt have to grind the gearbox for the flywheel, if you want more bottom end then you would gear it lower not higher like a 45/41, does your car ever have troom to top out or does it run out of room first? if it runs out of room then definately gear it down, might i ask what clutch you are running? the hpi racing clutch is pretty good depending on where it is set, but the thing that made the most difference for me was modifying my 18ss, you might not want to do it but its free and it works very well, there are ahandful of modding threads on RCU alone that are good, and i myself have successfuly modded 4 engines, the 18ss was the one that worked the best, it would get you alot more power all the way through the power band, i have pics if you would like to see them

on a side note, what brake are you running? i got some hyper 7 steel discs with some R40 brake pads and it always had alot of power to stop my car, heres a pic



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RE: Need some bottom end snap - 6/13/2007 6:44:13 PM   
almtx3



Posts: 266
Joined: 1/12/2007
From: Miami, FL, USA
Status: offline 		Yeah the car tops out on the long straight away, thats why I want to go to a 45/41 spur. I should feel a a slight difference in bottom end with those gears right?

Im running an MIP racing clutch and I have it shifting accordingly to the track. I get a solid pull on 1st gear round all the corners and a good 2nd gear shift right at the end of my 1st gears power band on the straight away. The MIP clutch was a great improvemnt over the stocker 3 shoe. The cars got a sway bar kit whick helps a bit but the best suspension upgrade has been the threaded shocks! It gives me greater adjustability and they travel so sweet. I just ordered an aluminum steering assembly from GPM to try to get rid of a bit of the slop from the stock steering assembly and I just picked up the graphite shock towers to get a bit more adjustability for the shocks.

Im running the HPI fiber brake. Pretty decent braking cant complain there. Your brake set up is awesome!

Yeah I would love to hear your engine tips. I would greatly appreciate it if you would email me them. I had a Tmaxx that I ported and removed a few shims from the head and that thing was insane, so Im not too afraid of moding an engine. I would also love to see some pics of your car if you dont mind. heres my email: alnsue21@hotmail.com

Thanks apollo!

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RE: Need some bottom end snap - 6/13/2007 8:26:19 PM   
hpi apollo



Posts: 2639
Joined: 5/13/2006
From: Georgetown, KY, USA
Status: offline 		well you want it to top out on the straight, if you gear it up (going down in teeth on the spurs) then your bottom end acceleration will suffer a bit and it will take longer to top out, sounds like your gear setup is good for now, what fuel percentage are you running?


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RE: Need some bottom end snap - 6/14/2007 3:44:35 PM   
almtx3



Posts: 266
Joined: 1/12/2007
From: Miami, FL, USA
Status: offline 		Odonell 20% - Whats your take on that? Should I step up to 30%?

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RE: Need some bottom end snap - 6/14/2007 4:53:16 PM   
hpi apollo



Posts: 2639
Joined: 5/13/2006
From: Georgetown, KY, USA
Status: offline 		for racing i would highly suggest going to 30%


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RE: Need some bottom end snap - 6/14/2007 5:15:21 PM   
almtx3



Posts: 266
Joined: 1/12/2007
From: Miami, FL, USA
Status: offline 		Im with you on that one. Been meaning to do that for quite some time now. I am a bit concerned with the cars temp. Its pretty hot here now, well into the 90's. I guess Ill just have to monitor that closely.

What temp was your car running at when you had it?

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RE: Need some bottom end snap - 6/22/2007 4:00:15 AM   
fox222


 

Posts: 63
Joined: 3/21/2005
From: Woodstock, GA, USA
Status: offline 		You can change your 1st gear pinion to purple or even yellow without changing 2nd. This will give you better take off without changing the top end.
Changing your pipe to a RD Logics or even the new pipe from HPI will make a big difference also.
Here is a chart for transmission ratios.


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RE: Need some bottom end snap - 6/22/2007 6:42:44 PM   
almtx3



Posts: 266
Joined: 1/12/2007
From: Miami, FL, USA
Status: offline 		Sweet chart fox. Thanks a million! I think Im gonna do that. I might go with a 1st gear purple pinion for now and test that out.

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RE: Need some bottom end snap - 6/22/2007 10:30:23 PM   
fox222


 

Posts: 63
Joined: 3/21/2005
From: Woodstock, GA, USA
Status: offline 		You will notice the difference.

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RE: Need some bottom end snap - 6/23/2007 12:45:46 AM   
SioXiE</