small motor ideas

[RFbuilt]

for the first post (takes a deep breath) heehe 

i understand thers a thread about small powerhouses  but i was wondering if we can have a good discussion on 1 particular configuration thats rather an odd ball motor for most..

(hopefully mr Jim Ratto will be interested in this ) hehe

motor on the hot seat :

85.5x74 - 1699cc 
mahle/cima or AA  piston and barrels
74mm stroke crank of choice
35.5x32 vw casting DP
Engle w120
dual Kadron 40's
8.8:1 static comp

use is : what id like to call a "cross trainer"  sumthing u drive on the streets (without dying hehe)  sumthing u can take to the local RWYB (circuit) tracks...  and maybe a run in the strip to see what it does..   

overall goal is a flexible motor.. that wont require a fully built trans (though i know there are some with stock trans with big motors)

for the 110$ avg. cost of the P/C and cb having a 74crank for about 180$ this could be a decent cheap motor build.. costing nearly as much as a 1585cc rebuild..

opinions? suggestions? throw a tomato? hehehe

[67worshipper]

you will have to go to a pro street box when funds allow.motor sounds interesting.keep everything balanced,i.e.crank,clutch,flywheel,rods,crank pulley.do some home porting on the heads and match port the manifolds(exhaust and inlet) .

[RFbuilt]

yes i understand about the trans issue (sooner or later  a built one is needed) 

balancing is also sumthing that will be done ( i think all motors should be, anyways , eben stockers)

didnt mention about porting since its a performance oriented build.. but yes it will be ported
and a good valvejob done to it..

[Lee.C]

might wanna check this thread dude 

http://cal-look.no/lounge/index.php/topic,3257.0.html

[RFbuilt]

yeah  ive been enjoying that thread for some time now prior to making this thread hehehe 

was just hoping to have a discussion if we have enough guys sharing the same interest in a 85.5x74 motor
and have a more concentrated discussion
like cam choices, revability, lifespan.. etc 

the JPM mouse motor is simply amazing i myt add hehe

[Zach Gomulka]

Why this configuration?? Are you limited to a 1700cc max for a race class or something? Why would you  build a 85.5x74 when a 88x69 is a cheaper and easier motor to build? Bigger bore also offers more headflow. My two cents is that the Kadrons are too small for that 120 cam. Once the cam starts to come on, the carbs will be near the top end of their range....

[Torben Alstrup]

I would look at the problem from another angle.

1. The Kads can easily keep up with a W120 cam, if they are equipped with the correct venturies and jets. - They will need a vacum advance distributor and modified carbs to run without flat spots. ( Maybe not, but its way easier to jet them right)

2. The 85,5 X 74 mm. is a good choice, as are the 88 X 69 mm. Its a matter of what you want to pursue in characteristics of the engine. - However, I do think that the combination of parts are, should we say less lucky.
- The stock piston rings do not like to be reved past 5700 rpm. The W120 cam will pull way higher rpms than that, if your heads are good.

I would go for forged pistons or reduce the cam duration.
T

[Jim Ratto]

Sounds cool
BUT one thing you need to keep in mind.

Stock Mahle cast 85.5 have a tough time clearing a stock 69 c/w crank, and they are going to have an even harder time clearing a 74mm.

I think cam and carbs can work fine. It will be "cammy" since your asking the metering circuits to "sense and read" two cylinders, that, are doing two different things, at the same time. I have ridden in 1776's with 120 and Kadrons and they ripped. Sounded awesome too.

Maybe used forged Mahle 85.5. They clear a 69mm c/w crank.

Just cost more. 

[RFbuilt]

zach ,torben, jim 

interesting thoughts..   and keeps me goin at it.. 

this is as much of a plan.. as an evolving list  for what to do..   

as Jim noted about stock mahle's and and Torben..   are there any ways goin around the ring issue?  is there a ring set that would work with the Mahle's to help the situation?

or maybe its time to check out DRD/darren's stroker 85.5s hehe   there is def a solution around that prob.. 

and yes the Kads will def be tuned.. i believe any carb should be.. anyways..  i have a wideband and datalogging system that i use on a different platform/make engine , and believe me.. i wont stop tuning the carbs til its really tuned..    ive read horror stories of.. "it runs ok"  "but not that ok" LOL 


the idea started as a rebuild 85.5x69 ,   then why not a 74 crank.. lol   though i know the 88x69 is a good config. already.. just thought why not try the different route..      maybe if things work out.. a nice 88x74 can be in the near future hehe

[RFbuilt]

not really looking for the "ultimate" small motor high hp set-up..   just a little oomph and boost here n there..

if a 1585-1678cc motor can be rebuilt and done good enough to give decent WHP.. 
maybe the added stroke will give some too?  kinda like a pseudo super90  engine.. 

if it runs as good as a stocker 1585 in the low end.. then im fine with that.. so long as  the 1585 runs out of breath first bfor this motor does..  (so its not the max whp im goin for)   

so its interesting, seeing good thoughts and advice..  thats the main goal right now.. to have a good discussion with the said configuration,

i wonder whats everyones thoughts on.. 35.5x32 heads, ported well, small CSA  with decent port velocity
wouldnt the bigger cam w120 (vs w110)  fair well..  if u get the port velocity.. keeping the valve opened longer should just help?

ofcourse given that everything is set up well.. and configured properly that is hehehe

what are your thoughts on that? (if im wrong.. please id be glad if sum1 smacks my head so i know haha)

[Torben Alstrup]

WRT the ring issue. I have not come across any solution that was worth looking into. Forged Mahle´s are also only about twice the price of stock, so its not worth to spend time on that.  Forged "A" piston clear a 76 crank, so no need for strokers.
As for heads, well, a set of DRD LS3CNC could be very usefull here. If you want to max the combo out, I would suggest a valve lift at about 0,460. 1,25 rockers on the intake alone will help the intake do its thing, eventhough the lift gets a tad too high. I´m not really a fan of the W110 for anything but power. Its rough on the valve train, makes the engine noisy and also have a tendency to heat up the heads at sustained high load. The W120 is better.
Another thing. if you have the fuel for it, bump the CR a little more.  With 9-1 you can run 95 octane Euro fuel. 9,5 - 1 requires 98 octane. i have run 10-1 on 98 octane, but that´s pushing it, and not suitable for high sustained load.

T

[RFbuilt]

as usual  good stuff torben..

i wonder what CB used in their mileage motor.. since its an 85.5x76    as far as clearing the counterweight crank..

i thought DRD's 85.5 stroker pistons was forged, or atleast clears the counterweights

if thats the case.. then a 85.5x78 sounds doable haha

[Torben Alstrup]

if thats the case.. then a 85.5x78 sounds doable haha

Now youre already wandering. The topic was 85,5 by 74 mm or close. A 85,5 by 78 is a totally different beast.
T

[RFbuilt]

hahaha no no it was a joke..  mocking myself (since its bin always like that)  one would come up with a small motor idea and end up goin the route of 1776,1915,1904 2276 etc

im sticking to the 85.5x74 idea..  im more interested in the "way" around the problems  than the way out of it and just doin a different configuration..   i guess id spend just to learn a lesson..  but then again il be fine with that..

[Harry/FDK]

hehe

[Taylor]

i wouldnt go 85.5 either,  u cant get a bigger valve in there unless u just want a little more torque.

[RFbuilt]

thats true...  but for 88 machine ins, and up.. the cost is nearly the same for forged 85.5's less machining

i have nothing against 88s, even 90.5s and or 94's    just that it snowballs from there
88s and above.. a 40x35.5 head would be preferable (adding cost)    if the portwork(quality) ends up being the same for 35.5x32

thats why i had this thing/idea for a weird config such as the 85.5x74     
we've seen too many ideal sized motors, with less desireable parts as a total 'system'   just to be able to run a conventional lay out
again i wouldnt want to go that way..

but guys it doesnt mean im not taking any opinions from u guys..  ur opinions help alot.. helps me fine tune the list/plan 

hehe  so keep it coming hehe.. a discussion towards "solving" the inherent problems that will be encountered.. would be great...

[Torben Alstrup]

i wouldnt go 85.5 either,  u cant get a bigger valve in there unless u just want a little more torque.

Why do you want a bigger valve ? Just make the 35,5 mm OR a 37 mm intake work its best. You will have plenty of flow for the cc and rpm.
T

[RFbuilt]

as always torben.. very good input..  and im glad it was sumthing i had asumed bfor..

yeah 35.5 intakes should be fine.. provided i ported well (mild) and whip up a good valvejob on it.. 
basing on throat dia. in % it should be able to provide enough..

a 37mm intake indeed sounds good.. and i had a thought about it too hehe

[Jim Ratto]

why not one of my favorite "tried and true" combinations? So easy to build and go fast with?
1914, K8, 40 x 35.5, 9.0:1, dual 2bbl Webers?

[RFbuilt]

ahhhh  nice nice!  because the 2bbl webers are sumthing i cannot afford for now.. cant promise i can get them by end of the year, next year or in 2 yrs.. hehe

[Jim Ratto]

ahhhh  nice nice!  because the 2bbl webers are sumthing i cannot afford for now.. cant promise i can get them by end of the year, next year or in 2 yrs.. hehe

90.5 x 69, stock heads, Web 110 simple, easy fun and fast. Use your Kadrons!

[Project_X]

what size kadrons you using?

[RFbuilt]

Kadron 40s

we have 95oct at the pumps and im fine using them for daily.. as far as cost goes..

[Neil Davies]

ahhhh  nice nice!  because the 2bbl webers are sumthing i cannot afford for now.. cant promise i can get them by end of the year, next year or in 2 yrs.. hehe

Scour the breakers yards for old Alfa Romeos... 36DRLA Dellortos cost me £25 ($50ish) a few years ago! If you haven't got the Kads already you should be able to piece together a Weber/Dellorto set up for about the same cost...

[RFbuilt]

its just hard being in Asia haha  and shipping is always an arm and a leg..

but yeah.. the weber idf's (possibly 44's)  are an option already noted.. but like i said.. i just dont know when il be able to get them
by end of this year? next year.. or in 2-3yrs hehe 

so... its not like im set on not running 2bbl carbs..  just not now..
the kads should be ok..  i for sure will take the time  to tune them.. using my wideband.. 
and i know i wont even expect it to be close to what idf's or 2bbl's can give...    but it should be better than a stocker carb when tuned..