Need some bottom end snap (Full Version)

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almtx3 -> Need some bottom end snap (6/12/2007 4:57:23 PM)

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



hpi apollo -> RE: Need some bottom end snap (6/12/2007 5:54:11 PM)

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



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

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.



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

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?



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

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..



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

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.



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

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
[IMG]http://i66.photobucket.com/albums/h265/hpinitroracer/metalbrakedisc.jpg[/IMG]



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

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!



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

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?



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

Odonell 20% - Whats your take on that? Should I step up to 30%?



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

for racing i would highly suggest going to 30%



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

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?



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

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.



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

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.



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

You will notice the difference.



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

[:D] nyc post i especially with the charts, veri helpful



fuzion18ss -> RE: Need some bottom end snap (6/26/2007 10:49:48 PM)

Which pipe do you have?

Rd Logics turbo II gave my car tons of snap...maybe a little too much (great pipe thx Apollo). I would just spin the tires with the stock gearing. Granted they were the stock rubber, but still i was [X(] and then [:D]

I swapped out to the 43 39 (?) combo and gained some traction. I didn't grind anything either (don't have a dremel with me) and the gears are still intact. There might be a little excessive wear, but i was curious and it didn't instantly strip them out.



almtx3 -> RE: Need some bottom end snap (6/27/2007 8:54:58 PM)

I got the JPL Turbo pipe. Way better than the stocker. I have heard about the Rd Logics turbo II but I purchased the JPL pipe before I knew abut the RD. Kinda regreting it but oh well. [:o]

Dont get me wrong, the car works great, its got killer grip Im just trying to squeeze every last ounce of performance I can out of the car. Im currently looking around all the LHS for the Gold pinion gears. 1st gear 17t and 2nd gear 21t. If I find them Im definately gonna give those a shot along with the Purple pinion gears just to experiment a bit with gearing. Im using the great chart Fox222 posted as my guide so I look forward to posting my results once I get the gears.

I also called HPI and they gave me a simple formula for gearing. The less teeth on your pinion gear the more acceleration you will have. Downside to that is you will loose top end speed. And vice versa for top end. The more teeth your pinion gears have the more top speed you will gain but in turn you will loose fast acceleration. They also recomended to keep the stock Spur combo for now and just mess with the pinion gears and see how that works out for my particular application. I also got alot of great advice from everyone here on the forums.

Im gonna have to do alot of trial and error experimentation here so I look forward to sharing my results with you guys.



fox222 -> RE: Need some bottom end snap (6/27/2007 11:19:46 PM)

al18ss,
Did you know that you can mix different color pinions? So if you want a lower 1st but keep 2nd as is just change 1st to purple or yellow.



almtx3 -> RE: Need some bottom end snap (6/28/2007 4:15:54 PM)

yeah I did - thanks Fox222. Im actually gonna go with the 17tooth 1st gear and 21tooth 2nd gear. Im definately gonna loose some top end speed but the track I run at is a bit more on the technical side so I think this gearing option should work out just fine. There is a long straight but I would rather sacrifice a bit of speed on that and gain some speed coming out of a corner. Thanks for the chart. I have been using that as my guide. Glad you posted it here. Maybe someone else can use it as well. I am still very willing to experiment, so if my initial combo does not work as intended, your suggestion of mixing pinion gears is definately a good one! Thanks again bud![sm=thumbup.gif]



almtx3 -> RE: Need some bottom end snap (7/10/2007 3:12:55 PM)

Finally got my car back together and I also have the new gold pinion gears. I should be heading out to the track this weekend to see how much of a difference those gears will make. Im also excited to see how the car handles after installing the aluminum steering assembly. Ill keep you guys posted.



Foxy -> RE: Need some bottom end snap (7/10/2007 6:49:37 PM)

If you want more snap, you should concentrate on the clutch, al. Later engagement. You want the gearing to top you out about 2/3s of the straight.



almtx3 -> RE: Need some bottom end snap (7/10/2007 8:04:11 PM)

good suggestion foxy42! I will definitely keep that in mind this weekend![;)] Thanks!

By the way - How's your car running? Have you taken it out lately?



Foxy -> RE: Need some bottom end snap (7/10/2007 8:18:32 PM)

Too busy lately, just got back from two weeks in portugal on business, been in seminars all week last week. This week wall to wall meetings, more seminars, then another working trip this weekend. It's crazy. I'll hopefully get the car out on Saturday and dust her off. [;)] Last time she was out she was running beautifully, unfortunately I wasn't! lol! They changed the track layout and even the direction. I couldn't get along with it at all. More practise required. [:D]



almtx3 -> RE: Need some bottom end snap (7/10/2007 9:07:15 PM)

I hear you Ive been pretty busy myself and haven't had a chance to take my car out as well. We were able to get jatohulks NT1 out to track for a little while last week just to get her all broken in properly and tuned for the track. If Im not mistaken he was using the set up you have on your car. All I can say is WOW! [X(] - It was a killer set up right from the start. The car got around the corners incredibly and the handling was dead on! We had an unfortunate run in with the wall so the front tire chunked and we didn't have any spare tires so that was that. The car held up great but Jato and myself need to get some more practice! The car handled great but the drivers needed help. [sm=confused_smile.gif] Man we were all over the place but it was a blast! Im looking forward to getting both cars out this weekend. Hopefully we will be able to keep the cars in one piece...



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