28 and 32 Engine Specs

[AllanQ]

I have gathered the specs for what I think are the more commonly used engines by our members. I hope members can use this as an easy reference for engine specs or comparing the specs when trying to decide on an engine to buy. I did not include prices because they vary depending on where you decide to purchase. If there are more engines you think should be added please let me know. Hope this helps someone out.

For actual HP specs, please check out Moto's thread on engine HP here.

Axial 28RR Spec 1

The 28RR Spec 1 is a .28 cubic inch big block engine featuring a machined cast aluminum heat-sink head for extra cooling, dual bushing aluminum connecting rod, true ABC chrome sleeve construction for durability, and a three needle 9.0mm slide carburetor (including 8.0 & 8.5mm optional venturi’s) with a composite body for better performance at higher temperatures. The carburetor features a factory re-set line on the high speed needle, and flush needles making re-setting, to baseline factory specifications, quick and easy. There is also an optional Turbo Button head available.
This is a direct bolt-in replacement engine for any .21+ engine mount, and will accept most aftermarket shaft drive starting systems.
Axial 28RR Spec 1
Size: .28 cubic inch/4.6cc
Maximum RPM: 38,500
Bore: 18.25mm
Stroke: 17.5mm
Construction: ABC
Heat-sink Head: Green Anodized (optional Grey available)
Carburetor: 9.0mm Composite Slide Carburetor (includes optional 8.0 & 8.5mm venturi’s)
Carburetor Adjustments: 3 Needle, Flush Settings
Case: Black Aluminum, Rear Exhaust
Connecting Rod: Dual Bushing
Sleeve: 7 port
Starting system: Pullstarter
Recommended Glow Plug: Cold-5 Power Plug
Features
• Lower CG engine head with increased cooling capacity
• True ABC construction
• Standard button head (optional turbo head available)
• Pull start included
• Optional rotostart backplate available
• Optional bumpstart backplate available for racers (uses AX0090 32 bumpstart backplate)

Axial 28 Spec 1s

The 28 Spec 1s is a .28 cubic inch big block engine featuring a machined billet aluminum heat-sink head for extra cooling, dual bushing aluminum connecting rod, true ABC chrome sleeve construction for durability, and a three needle 8.5mm slide carburetor with a composite body for better performance at higher temperatures. The carburetor features a factory re-set line on the high speed needle, and flush needles making re-setting, to baseline factory specifications, quick and easy. There is also an optional Turbo Button head available.
This is a direct bolt-in replacement engine for any .21+ engine mount, and will accept most aftermarket shaft drive starting systems.
Specifications
Size .28cubic inch/4.6cc
Maximum RPM 36,000
Bore 18.6mm
Stroke 16.9mm
Construction ABC
Heat-sink Head Grey Anodized Aluminum
Carburetor 8.5mm Composite Slide Carb
Carburetor Adjustments 3 Needle, Flush Settings
Case Black Aluminum, Rear Exhaust
Connecting Rod Dual Bushing
Sleeve 8 port
Starting system Pullstarter
Recommended Glow Plug Cold-5 Power Plug

Axial 32 Spec1s

The 32 Spec 1s is a .32 cubic inch big block engine featuring a machined cast aluminum heat-sink head for extra cooling, dual bushing aluminum connecting rod, true ABC chrome sleeve construction for durability, and a three needle 9.0mm slide carburetor (including 8.0 & 8.5mm optional venturi�s) with a composite body for better performance at higher temperatures. The carburetor features a factory re-set line on the high speed needle, and flush needles making re-setting, to baseline factory specifications, quick and easy. There is also an optional Turbo Button head available.
This is a direct bolt-in replacement engine for any .21+ engine mount, and will accept most aftermarket shaft drive starting systems.
Engine Specifications
Size .32cubic inch/5.2cc
Maximum RPM 34,000
Bore 19.5mm
Stroke 17.5mm
Construction ABC
Heat-sink Head Grey Anodized Aluminum
Carburetor 9.0mm Composite Slide Carburetor (includes optional 8.0 & 8.5mm venturi�s)
Carburetor Adjustments 3 Needle, Flush Settings
Case Black Aluminum, Rear Exhaust
Connecting Rod Dual Bushing
Sleeve 8 port
Starting system Pullstarter
Recommended Glow Plug Cold-5 Power Plug

OS 28XZ

The larger head aids in cooling, and is a 2-piece construction with inner head button.
A sealed front bearing and high-performance inner bearing are part of the new crankcase design.
The high-performance con rod features oiled bushings.
​

Three needles enhance fine-tuning on the 21J slide-valve carb.
​

Comes with a high-performance P3 hot turbo plug.
​

SPECIFICATIONS
Stock Number: OSMG2074
Displacement: 0.284 cu in (4.65 cc)
Bore: 0.728 in (18.5 mm)
Stroke: 0.681 in (17.3 mm)
Practical rpm: 4,000-38,000
Weight: 13.1 oz (375 g)

OS 30VG

[FONT=Arial, Helvetica, sans-serif, Verdana, Trebuchet]
[/FONT]Available in three SG-crank versions, including a recoil start model and an SR model purpose-designed for the HPI Savage.
Rear-exhaust design.
Machined aluminum piston.
Double-bushed, tapered aluminum conrod for minimal wear and weight.
3-port liner.
Rubber-sealed front bearing reduces teardowns — enlarged rear bearing minimizes vibration and improves load-bearing capacity.
Oversized balanced crankshaft for added strength and smooth, vibration-free operation.
Insulated carb sleeve prevents heat-related vaporization and predetonation.
Rubber shaft boot preserves smooth, easy slide-valve operation.
[FONT=Arial, Helvetica, sans-serif]Engine[/FONT] Displacement[FONT=Arial, Helvetica, sans-serif](cu in)[/FONT] Bore[FONT=Arial, Helvetica, sans-serif](in) [/FONT]Stroke[FONT=Arial, Helvetica, sans-serif](in) [/FONT][FONT=Arial, Helvetica, sans-serif][SIZE=-2]
30VG (P) [/SIZE][/FONT][FONT=Arial, Helvetica, sans-serif][SIZE=-2]0.298 cu in (5 cc) [/SIZE][/FONT][FONT=Arial, Helvetica, sans-serif][SIZE=-2] 0.728 in (17.5 mm)[/SIZE][/FONT][FONT=Arial, Helvetica, sans-serif][SIZE=-2] 0.7165 in (18.2 mm)[/SIZE][/FONT][FONT=Arial, Helvetica, sans-serif][SIZE=-2]
[/SIZE][/FONT]

LRP Z.28R Spec 3

rear exhaust
slide carburetor
SG shaft
ABC piston and sleeve
rpm-max 38,500rpm*

 

[Blazer X]

Rep for you, this should be a sticky so people can add to it.

 

[AllanQ]

F4.6, K4.6 and K5.9 Specs

F4.6

FEATURES: Composite construction slide valve,
7.5mm 3 needle carburetor,
high speed needle, idle screw and low speed needle are set flush with the carburetor body for factory settings
8 port chrome plated brass sleeve ABC cylinder construction, "A"luminum piston with a "B"rass cylinder that is "C"hrome plated Purple anodized billet aluminum heat sink head Round rear exhaust port Cast aluminum crankcase with heatsink fins
Machined pilot shaft crankshaft with collet preinstalled
Knife-edge billet aluminum connecting rod with dual bushings.
High flow 2-stage air filter dramatically reduces intake restriction as it smoothes and straightens air flow Two year limited warranty

INCLUDES: Nitro Star .28 F4.6 glow engine Glow Plug - HPI R5 cold plug (HPIG1504 for a replacement) Dual Stage Air Filter (HPIC7198 for replacement) Instructions and exploded views

SPECS: Height/bottom of Mounting Flanges/top of Cylinder Head: 4" (101mm)
Height/bottom of Crankcase/top of Cylinder Head: 4.5" (114mm)
Length from Pull Starter to Front Bearing: 3.3" (84.5mm)
Length from Pull Starter to end of Crankshaft: 4.6" (117mm)
Width at Mounting Flanges: 1.81" (45.9mm)
Mounting Hole Center Same Side: .82" (21mm)
Mounting Hole Center Opposite Side: 1.42" (36mm)
Bore: 18.68mm
Stroke: 16.6mm
Crankshaft diameter: 5mm (clutch bell area)
Crankshaft diameter: 6.7mm (threaded portion) Displacement: 4.6cc (.28 ci)


K4.6

FEATURES: Composite construction slide valve, 3 needle carb with hand
adjustable high speed needle (the stock carb settings are made flush
for convenient "back to factory settings")
8 port chrome plated brass sleeve
True ABC cylinder construction
Purple anodized machined aluminum heat sink head
Rear exhaust round port
Cast aluminum crankcase features heatsink fins
Machined pilot shaft crankshaft with collet preinstalled
Knife-edge billet aluminum connecting rod with dual bushings.
Dual stage air filter dramatically reduces intake restriction as it
smoothes and straightens air flow


INCLUDES: Nitro Star .28 (4.6) glow engine
Glow Plug - HPI R5 cold plug ( for a replacement)
Dual Stage Air Filter ( for replacement)
Instructions and parts break down


SPECS: Crankcase: 3.29 inch (83.5mm) (from rear of case to front without shaft)
Height: 4.40 inch (111mm) (from bottom of case to the top of the head)
Width: 1.81 inch (mount flange)
Mount Holes: 1.42 inch (measured from center to center width)
Mount holes: .82 inch (Between holes front and back)
RPM: Max 39,000 RPM
Crankshaft diameter: 5mm (clutch bell area)
Crankshaft diameter: 6.7mm (threaded portion)
Crankshaft screw: 3 x 12mm caphead screw
Capacity: 4.60cc (.28 ci)


K5.9

FEATURES: Fits all versions of the current glow powered HPI Savage ABC piston and liner construction, "A"luminum piston with "B"rass cylinder liner that is "C"hrome plated
Three needle composite bodied slide valve carburetor with 9.5mm diameter inlet
Twelve fin aluminum heat sink cylinder head,
gun metal gray in color
SPECS: Displacement: .36 cu in (5.9cc)
Carburetor Settings- High Speed Needle: Flush with groove Low Speed and Mid Range Needle: Flush with carb body Idle Adjustment Screw: Set after high speed needle is adjusted-set high enough to keep engine running smoothly but not engage the clutch or turn the wheels Refer to manual for more detailed carburetor setting info
Height from Crankcase Bottom to top of Cylinder Head: 4.4" (112mm)
Height/bottom of Mounting Tab to top of Cylinder Head: 3.8" (97.5mm)
Distance between Mounting Hole Centers Same Side: 0.87" (22mm)
Distance between Mounting Hole Centers Opposite Side: 1.5" (38mm)
Length from Starter to end of Crankshaft: 4.4" (112mm)
Length from Starter to Front Bearing: 3.3" (83mm)
Width at Mounting Tabs: 1.8" (45mm)
Diameter of Cooling Head: 2.4" (60mm)

 

[Bankrupter]

Looks like Allan was board today... Nice Allan! I didn't know the OS was ABL. So I learned something today! :resp: Edit in their true HP#s Off megas dyno thread its a sticky in this section...

 

[scrogathon]

Nice thread, If this gets sticky it will deff help alot of people, we should also have some testimonials of the motors too.

 

[Jeremy]

Its a sticky .. Thank you Allan . and to everyone else that has contributed ..

Please keep adding more engines

 

[AllanQ]

By request, here are the specs for a Picco .28.

[FONT=Verdana, Arial, Helvetica, sans-serif]- ENGINE SPECIFICATIONS -[/FONT]​

RPM 34,000
CARB TYPE SLIDE
CRANK SG Shaft
CONSTRUCTION ABC
ENGINE CASE SIZE .21
ENGINE BORE SIZE .28
TYPE REAR EXHAUST
PORTS 9 ports
DISPLACEMENT .28 c.i., 16.8 stroke
CRANKSHAFT Heavy Duty Crankshaft 14mm
CARBURETOR Composite, 8mm insert, changeable
PLUG TYPE Standard Plug - Pull start

 

[Grumpy1822]

Its a good thing what you did. The problem is that they are all factory claimed specs and they all use different ways to determine hp and torque. The Xdyno is probably the closest thing we have for a real comparison. None of these engines will ever see 3 hp. Most are in the 1.5-1.9 range. Adams modded Picco topped at 2.3hp on his dyno. The graph is on his site I think. I'll give you an A+ for effort though.

 

[AllanQ]

Thanks grumpy. I added a link to Moto's engine HP thread so everyone can get the real HP numbers. I am going to go back and remove the HP claims since they are not accurate.

 

[mulisha770]

hi, i have a hpi 4.6 and i find it a pain to tune. which of these engines are the easy and best to use??

 

[Crash]

hi, i have a hpi 4.6 and i find it a pain to tune. which of these engines are the easy and best to use??

you have the easiest to tune

check for airleaks if you are having trouble with your tune

 

[mulisha770]

i lost my mid range needle and ever since i put a new one in it doesnt run properly. i put back to factory setting but i would like to know how many turns out from fully in it is?? that way i can get in bang on. cheers for your help

 

[faisalbasha]

i really think you should add the NEW picco p3 .28

its definately in the ---------top 3 of all time---------

 

[AllanQ]

The p3 is in post 7

 

[PhillH]

Crash is right, my 4.6 was a real pain, I couldn't get it to hold a tune for more than 10 mins. I pulled it apart and sealed it ( you can find how to on this site) and tuned it after putting it back together and haven't touched it since. It must've had a leak somewhere from brand new. I'll seal a brand new engine before I even run it next time.

 

[fastlane01]

I have a XTM 457 6 port and it tunes well and runs like scalded dog

 

[xll-SavageX-llx]

i was going to get the axial .32 spec 1s but i heard that the K4.6 HO has more power for my kinda stuff ([-BaShInG-])

lol!

 

[Crash]

i was going to get the axial .32 spec 1s but i heard that the K4.6 HO has more power for my kinda stuff ([-BaShInG-])

lol!

The 32 has more toruqe

The 28 has more speed

I own the 32 and 3 28's

I prefer the 28's

 

[frddyj]

i was going to get the axial .32 spec 1s but i heard that the K4.6 HO has more power for my kinda stuff ([-BaShInG-])

lol!

i have a k4.6ho, F4.6 modded & picco .28 modded. considering getting the HO modded after my buddie inspects it & lets me know if its worth it (it came to me used).

My LHS tells me that the HO was designed to rev higher & faster so i'm thinking that moving up in displacement (from a .28) may give you less rip than you already have.

To AllanQ plus reps my friend, you did a great job with this thread.

 

[frddyj]

you have the easiest to tune

check for airleaks if you are having trouble with your tune

+1. another factor for me was the stock tank. my f would not hold a tune or stay running when i added the THS pipe. did mid-tank conversion & it holds a perfect tune. i love this mill.

 

[AllanQ]

Thanks frddy!!! :resp:

 

[redneck]

this is a great thread

 

[soulja]

WHICH 4.6 DO YOU HAVE??? the f or the k???

 

[fastlane01]

I like the XTM 457 6 port. It's easy to tune and solid. I run a SH .28 8 port 457 which is basicly the same exact engine with 2 extra ports and that is one bad mutha. Can't beat em for the price and performance. Just to compare, my fellow basher has a 4.6 hpi on 30% and I run 20% he's lighter and I am faster! I was also told that SH ,hpi,xtm and a few more engines are made by the same company

 

[xll-SavageX-llx]

♦ K4.6 HO ♦

• Specifications for K4.6 High Output (#15204)
• Displacement: 4.59cc
• Bore: 18.6mm
• Stroke: 16.9mm
• Practical rpm : 3,100 ~ 39,500 rpm
• Maximum Horsepower at RPM: 2.95 hp @ 38,000 rpm
• Maximum RPM : 41,000 rpm
• Carburetor Type: Composite Slide
• Bore: 9.0mm with 8.0mm and 8.5mm reducer

 

[angellewalsh]

hi, i have a hpi 4.6 and i find it a pain to tune. which of these engines are the easy and best to use??

get rid of it i have the same problem,get a 2 needle carb and just tune the hsn. like a pico

 

[Nudist]

One more -

Axial 28RR-2

True ABC sleeve construction for durability. Composite 9.0mm 3 needle slide carburetor for improved performance at higher temps and quicker response (includes 8.0 and 8.5mm optional venturi’s). Carburetor features flush needles factory setting for quick and easy resetting to factory specifications.
Reliable pull start – no starter box needed. Machined aluminum heat sink head features a lower CG design with increased surface area for better cooling
Black Aluminum crankcase
Black Aluminum Heat Sink with Laser Etching
Dual bushing aluminum connecting rod
Options:
A. Turbo button head available
B. Roto-start backplate available
C. Bumpstart backplate available

Part numbers and EAN Codes

• Axial 28RR-2
• Size - .28 cubic inch/4.6cc
• Maximum RPM - 39000 RPM
• Bore - 18.25mm
• Stroke - 17.5mm
• Construction - ABC
• Heat-sink Head - Axial Black
• Carburetor - 9.0mm Composite Slide Carburetor (includes optional 8.0 & 8.5mm venturi’s)
• Carburetor Adjustments - 3 Needle, Flush Settings
• Case - Black Aluminum, Rear Exhaust
• Connecting Rod - Dual Bushing
• Sleeve -7P
• Starting system - Pullstarter
• Recommended Glow Plug -Cold-5

 

[Bankrupter]

Maximum RPM - 39000 RPM

lol do they know how high that is for a .28 ... I love MFGR specs always good for a giggle

 

[xll-SavageX-llx]

One more -

Axial 28RR-2

Here is the real specs for a Axial .28RR
Axial Racing .28 Spec I S 1.43 @ 22,800 rpm 75.61 oz-in @ 18,000 rpm 35,000 rpm AX001 $160

 

[Bankrupter]

Here is the real specs for a Axial .28RR
Axial Racing .28 Spec I S 1.43 @ 22,800 rpm 75.61 oz-in @ 18,000 rpm 35,000 rpm AX001 $160

Brando I think Spec I S is the normal 28 or the HPI K4.6 the RR did put out more but was a headache in its first version. had QC issues...