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L28 Street Build Budget


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#1 Kavs

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Posted 29 March 2017 - 12:47 PM

Hey guys, looking at rebuilding and going down the ITB path. The car does not get much of a work out and I mainly want more 0 - 100 fun. Spending a little on head work and a stage 2 cam and hoping to get away with 4 - 5k for the ITBs and EMS. I'm not overly schooled in this and no longer have the time to do it, so i'll be outsourcing all of it. Any info would be great!

 

Is it necessary to go down the forged internal or flat tops to achieve this?

 

What are the must have items?

 

Is a standard gasket kit ok?

 

How much should I expect to pay for a mild performance build (ball park)

 

Am I delusional in thinking 8 - 10K is possible for the above?

 

Thanks guys,

 

Kavs

 

Also pics I forgot to put up 2 years back, cheers for the spoilers Gav came up well back ones bubbling a bit but might the old oil based paint.:)

19621_942461809118311_351327624704578530

12592327_1097821036915720_55951665568664


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#2 gav240z

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Posted 29 March 2017 - 02:28 PM

Car looks good, I regret selling the front lip. Although I can probably find another in time.

 

If you get a chance I'd like to see more photos of how the rear "ribbed" spoiler turned out?

 

In terms of your build I believe Lachlan (Lurch) is doing a similar kind of build.

http://www.viczcar.c...rchs-l24-build/

 

Budget I believe is similar (maybe minus cost of Triple 44s)...



#3 Lurch ™

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Posted 29 March 2017 - 02:38 PM

Hey guys, looking at rebuilding and going down the ITB path. The car does not get much of a work out and I mainly want more 0 - 100 fun. Spending a little on head work and a stage 2 cam and hoping to get away with 4 - 5k for the ITBs and EMS. I'm not overly schooled in this and no longer have the time to do it, so i'll be outsourcing all of it. Any info would be great!

 

Is it necessary to go down the forged internal or flat tops to achieve this?

 

What are the must have items?

 

Is a standard gasket kit ok?

 

How much should I expect to pay for a mild performance build (ball park)

 

Am I delusional in thinking 8 - 10K is possible for the above?

 

Thanks guys,

 

Kavs

 

Also pics I forgot to put up 2 years back, cheers for the spoilers Gav came up well back ones bubbling a bit but might the old oil based paint. :)

 

To buy all the EFi gear AND build a performance engine for $8k to 10k?
Ain't going to happen I'm afraid - especially if you are going to outsource all the work.

To buy all quality off the shelf EFi parts, you need to budget at LEAST $6k

 

250hp on standard cast pistons & rods is doable. Any more than that, it'd be wise to upgrade to forged pistons & H-beam rods, just for reliability.

 

A standard 'KP' brand gasket set is fine as long as you stay under 88mm (IIRC)

 

As for the engine build, you'd have to speak with someone like Les Collins, but from previous experience a rebuilt STANDARD L28 comes in at $6k

$8k to $10k is more realistic budget for around the 250hp+ mark.



#4 dat2kman

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Posted 29 March 2017 - 05:04 PM

You say you want better 0-100kmh capability??
Leave it alone, and just throw in a 4.4 ratio R200 diff.
Live with that for a few months, then maybe re-visit your "budget plan" above.

Far easier, quicker and cheaper way to get what you almost want.
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#5 TomC18

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Posted 30 March 2017 - 10:11 AM

and there's a 4.375 R200 LSD for sale right now.... in parts for sale  :)

 

Could always pop it in until you realise it's too short for country trips



#6 Kavs

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Posted 30 March 2017 - 10:57 AM

So no good for cruising at 100?



#7 Cozza

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Posted 30 March 2017 - 11:15 AM

I got a 4.6 and can confirm it is not ideal for highway trips. Great for short tracks though. 👍
Changing your diff ratio is by far a cheaper option though. And, later, when you do build a motor, you will have a coupe ratios to choose from for the various tracks you try out 😀

#8 dat2kman

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Posted 30 March 2017 - 11:19 AM

Very difficult to have a compromise car!
You say initially 0-100kmh fun
But, then concerned about rpm at cruising speed
What do you want, vs what can you put up with?

#9 Kavs

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Posted 30 March 2017 - 11:52 AM

Not expecting much comprimise, Toms comment "Could always pop it in until you realise it's too short for country trips" suggested it being a bad idea.

I'm not claiming to be the expert here, that's why I'm asking not answering.

Can't see myself at the track. I go to work in it and sometimes through the hills. 



#10 CBR Jeff

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Posted 30 March 2017 - 03:24 PM

A 4.4 ration (if you can get one) is a nice compromise. Or just have two diffs with different ratios and change them depending on what you are going to use it for over the next period of time.

It takes less than an hour (one up with practice) to swap a diff.

Jeff



#11 dat2kman

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Posted 30 March 2017 - 07:57 PM

Or run a bigger diam rim with a tallertyre, effective ratio change right there, to reduce hwy cruise rpm.
Throw on some fat low profile rubber for the fun stuff!

#12 TomC18

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Posted 31 March 2017 - 10:17 AM

I think generally a 4.1 is a good highway compromise, 4.4 (actually the 4.375) just lifts your 100kph revs so its a bit buzzy, but great fun through the twistys...

As Jason says, if you run bigger road tyres it can help, I ran a 4.625 in the roadster for a while with a 185/60/14 track tyre and a 185/75 road tyre to give almost 10% higher road speed and more suspension compliance...

 

To get an idea for cruising don't use 5th, as that's about a 15% overdrive (I think?!), so driving in 4th with your current diff would be like 5th with a 4.3 or thereabouts... obviously all the lower gears would be shorter too...



#13 gav240z

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Posted 31 March 2017 - 11:14 AM

What sort of RPM would your engine sit at on a freeway with a 4.4 diff and tall 5th gear (say 280zx gearbox 5th)?



#14 CBR Jeff

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Posted 31 March 2017 - 11:56 AM

Depends on the roling diameter of your tyres but it's easy to do the maths.

Jeff.

#15 dat2kman

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Posted 31 March 2017 - 12:26 PM

What sort of RPM would your engine sit at on a freeway with a 4.4 diff and tall 5th gear (say 280zx gearbox 5th)?

Most of us racey/targa guys use a free basic downloadable program by Peter Ogden, called Gearcalc.
Enter into known data, it spits out things like max rpm speeds, max torque speeds, rpm drops on each gear upchange.
Then start playing around with input data, ie diff ratio, tyre size, gear ratio, peak hp rpm, peak torque rpm,,gets quite informative, certainly for different tracks

Re gearbox fifth gear, there are a few available,from a long legged loping 0.752, a 0.832, a 0.85, and a expensive 0.89, which gives the least amount of rpm drop on 4>5 upchange, keeping engine at peak torque (race/rally/tarmac thing!)

Back to the OP, the lowest cost performance upgrade will be diffratio change, add in a lsd. Next a gearbox change to an early 260Z box, the one with the 2.9 first gear. He can leave the stock 5th of 0.83, but, if hwy running is a concern, swap it out for a 0.75 fifth gear ( btw I have a few of those if peeps are chasing!)
Next, go to work on suspension and brakes.

I''ve just saved him $10,000, and the car will GO, Stop and Turn!

#16 Gareth. J.

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Posted 31 March 2017 - 04:48 PM

Here is the figures I did a while ago with my setup. With a 24.8582" tyre dia (225/50/16), 3.9 diff and 0.745 fifth you'd be doing 2,450RPM at 100kph.

I switched out the 0.745 for the 0.833 fifth and added a Kameari CR set.. For me running the 4.11 rear and the original 71b box 0.864 fifth I was doing 104.06kph at 3100RPM. Now with the 4.375, the RB20DET 71C with new 0.833 fifth I'm doing 103.96kph at 3100rpm. I dont do much hwy driving, 2hrs is about the max and if I get worried by it I slow down or speed up a little. I think it's fine on the highway, as long as I'm not going to do an 8hr trip at 110kph.

Your figure will differ a bit cause of the 0.864 fifth.

It's a completely different beast. The diff ratio change will transform the car!

Edited by Gareth. J., 31 March 2017 - 04:49 PM.


#17 dat2kman

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Posted 31 March 2017 - 08:30 PM

Try 7800 rpm down Conrod, with 225/50x15 tyres, and 0.83 fifth,,,,,,,




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