PDA

View Full Version : Help and advice needed.



ajcav86
29-06-12, 11:25 AM
I am new to this, looking to do a build with my Dad (he used to rebuild mini's so not complete amateurs) but never done a V8 muscle... We have decided on a Dax and not really working to budget limitations so want to build a dream car.. (tho if can be helped keeping under 40k + vat would be nice)...

We are thinking of a custom Chevy 350 stroked to 383 (is that the best stroker to go to?) We are hoping to get between 500-550bph but still be able to drive it around corners lol... We were going to put a Tremac TKP 600 on it. We are not sure on clutches.. We were looking at the SPEC ones or the Mcloeds, but not sure if they are the most appropriate or which one to go for... Any thoughts on fuel injection? If we did go for it were thinking of either the 'FAST EZ EFI' or one of the edelbrock ones. Does anyone have any thoughts or experiences of these... Are there any other big decisions to do with the insides we have forgotten? Any ideas of suspension and Limited Slip Differential?

Sorry a lot of questions but we are trying to sort a full design and kit list before we order so we know exactly what we are doing and spending. All help and suggestions is very much appreciated.

Lex

ajcav86
29-06-12, 11:26 AM
It is probably worth pointing out we want the car for weekend driving and the odd track day.. An we are not traditional purists lol

Lloyd Barnes
29-06-12, 12:06 PM
Welcome to the forum Lex,

the 383 is generally the accepted best stroker kit for the small block Chevy, adds plenty of torque without ruining the engines abiity to rev. 5-550 hp is doable but is going to also need a serious cam and heads (my 383 with AFR 195 heads would have been running a more usual between 410-450hp), and therefore your fuel injection is a decent idea as it will help to retain a better idle. With your budget perhaps have a look at the TWM systems, (Have a nosey in Craggle or Clarksons gallery)... they do look the dogs danglies!

Suspension is pretty much decided by the kit you go for, with Dax you have the choice of the earlier standard XJS based suspension or the later DeDion suspension using XJ40 parts. Many folks run LSD's but having them derated to suit the weight of the car is strongly recommended.

Enjoy the build

cobracol
29-06-12, 01:08 PM
Hello and Welcome Lex (Great name!) 500+ bhp is an awfull lot of power out of a stroker for use as a non racer, and you will only be able to achieve that with some serious heads and cam, however a big cam will also affect its road manners, and tend to make it jerky and hard work in traffic, and i would suggest going for an old school 400 block or maybe one of the later LS7s to get relatively easy going 500hp, i could also suggest an LS9 but even with a 40k budget you may struggle, my 383 is 420ish and is just about ok in traffic with a little bit of lurching at 25mph in fourth, but mine was built to produce the goods when you spank its ass, in my opinion there is no point in having the sort of power that just spins wheels at the lights (though it will still do that), regarding lsd, personally i would always go for it,

Chimeara
29-06-12, 01:35 PM
With 40K in your pocket build an LS based car. Avoid that EZI EFI system like the plague, biggest heap of $h1T I ever did have the mis fortune of using once.

ajcav86
29-06-12, 01:46 PM
Thanks so much, really appreciate the feedback. I was wondering if you had any links for the TWM system?.. Also what performance are you getting from the 450bph? If we could get 3.8 or less 0-60 and 165mph+ from 450 then would prob be happy with that..

ajcav86
29-06-12, 01:49 PM
Hello and Welcome Lex (Great name!) 500+ bhp is an awfull lot of power out of a stroker for use as a non racer, and you will only be able to achieve that with some serious heads and cam, however a big cam will also affect its road manners, and tend to make it jerky and hard work in traffic, and i would suggest going for an old school 400 block or maybe one of the later LS7s to get relatively easy going 500hp, i could also suggest an LS9 but even with a 40k budget you may struggle, my 383 is 420ish and is just about ok in traffic with a little bit of lurching at 25mph in fourth, but mine was built to produce the goods when you spank its ass, in my opinion there is no point in having the sort of power that just spins wheels at the lights (though it will still do that), regarding lsd, personally i would always go for it,

Deffinately would rather a more traditional block than a LS engine as when we went to dax they had the demo car with an 8.2L, one of the owners cars with a 383 and another car with an LS and didn't like the look or sound of the LS at all...

So do you think 500+bph is too much for road use? What would you recommend to make the car 'Bat out of hell' fast but still handle very well and have good 'manners'

Also would you have any suggestions on LSDs? possibly links? Thank you so much!!

ajcav86
29-06-12, 01:50 PM
With 40K in your pocket build an LS based car. Avoid that EZI EFI system like the plague, biggest heap of $h1T I ever did have the mis fortune of using once.

Also will take your advice and def avoid the FAST system thanks, but I am just not a fan of the LS engines... :)

craggle
29-06-12, 02:19 PM
Hi Lex and welcome to the forum. :)

There is a link to my gallery below in my signature that Lloyd mentioned above.

As for TWM take a look here. Borla-TWM Induction Official Website (423) 979-4045 (http://www.borla.com/products/induction/Home/Home-FR.html)
TWM or Borla as they are now only make the throttle bodies so you will also need an aftermarket ECU, injectors and ignition system. Mine runs an Accel DFI Thruster system with dual sync distributor and it runs great but there are many options for ECU's and you can use coil packs rather than a distributor.

Have fun deciding but at least the hard decision of what car to go for is out the way already. :)

Craig.

cobracol
29-06-12, 02:32 PM
Deffinately would rather a more traditional block than a LS engine as when we went to dax they had the demo car with an 8.2L, one of the owners cars with a 383 and another car with an LS and didn't like the look or sound of the LS at all...

So do you think 500+bph is too much for road use? What would you recommend to make the car 'Bat out of hell' fast but still handle very well and have good 'manners'

Also would you have any suggestions on LSDs? possibly links? Thank you so much!!


No, i didnt say 500hp is too much for road use (though many might say it is), i said its a lot to get out of a 350 stroker, a 400 stroker will give more power out of the box, and be able to cam it, to a reasonable limit, without affecting its every day road manners as much, imho you cannot have too much power, but you can have more power than you can use, before you simply loose traction (Oops! there i said it!), on the subject of efi, i would avoid it if at all possible, unless you are very freindly with a local car electronics wizzard, or indeed are one!

As an afterthought if you really are a power crazed madman, then go for a big block which are not as sensitive to large cams, but of course mph will suffer

ajcav86
29-06-12, 03:04 PM
No, i didnt say 500hp is too much for road use (though many might say it is), i said its a lot to get out of a 350 stroker, a 400 stroker will give more power out of the box, and be able to cam it, to a reasonable limit, without affecting its every day road manners as much, imho you cannot have too much power, but you can have more power than you can use, before you simply loose traction (Oops! there i said it!), on the subject of efi, i would avoid it if at all possible, unless you are very freindly with a local car electronics wizzard, or indeed are one!

As an afterthought if you really are a power crazed madman, then go for a big block which are not as sensitive to large cams, but of course mph will suffer

I thought EFI meant improved throttle response and (cringe better MPG). My next door neighbour owns a 2nd hand car dealership so I could always make use of his mechanic for any electrical needs :) I was just under the impression that carbs went out of tune occasionally and weren't as efficient? I am showing my 'greenness with old school muscle here aren't I?..

I was also advised that the weight of a big block could also negatively effect handling?.. Not a power madman just trying to build a really fast well handling dream car... :)

craggle
29-06-12, 03:32 PM
Carbs can be fine and when setup they do work very well. They are usually a compromise though in certain parts of the engines running as you can normally only tune the wide open throttle, mid range and idle so a carb well setup for drag racing with wide open throttle may be less efficient slightly off full throttle but for the cost and ease of fitting carbs, they really can't be beaten.

I went EFI as I liked the look of it and I was offered the kit at a very reasonable price. I would certainly do it again though and I think EFI can be better tuned to the full use of the engine and can prove more economical in the long run. All modern cars are EFI so they use less fuel and meet modern emissions standards, That is the only reason carbs are now considered old fashioned.

How many miles do you intend to do per year? I know that is a how long is a piece of string question but if you spend £5K fitting an all singing and dancing EFI kit to save 4 Mpg then you need to drive a hell of a long way to make a saving over a £1k Carb and manifold.

If you have the means though go for EFI at the start of the build as it will be easier to fit it during the build than after like I did.

Craig.

craggle
29-06-12, 03:43 PM
Oh, Don't be afraid of electrics either. My EFI kit was very simple to fit and as long as a bit of common sense is used you won't have any issues. :)

I drove my car with both the carb and the EFI on it and I would say the advantages and disadvantages of both are....

The EFI starts first time every time, no pumping of pedals needed and it even ticks over on it's own when cold.
The power from the EFI seems more progressive. There was always a noticeable step in power from the carb when the secondary circuits came into play but the throttle bodies just give progressive power right through the rev range.
My 50mm throttle bodies have more induction noise.
There are no filters on my engine now, No room to fit them under the bonnet.
You need a laptop to tune and play with the settings.

I'll let you decide which are advantages and disadvantages. :)

Craig.

britbits
29-06-12, 04:43 PM
Hi i am with Craig with the same set up and i find you can program the right set up for your driving ability , anything from mild to completly wild , almost undrivable on the highway, but ok for track, Dave B

Lloyd Barnes
29-06-12, 05:06 PM
Also what performance are you getting from the 450bph? If we could get 3.8 or less 0-60 and 165mph+ from 450 then would prob be happy with that..

I ran my car at santapod... I don't have a 0-60 time but I was running 113mph in 12.3 seconds. 3.8 secs sounds about right, given the 60ft times we were getting. However that doesn't tell the full story as these cars struggle for traction off the line on street tyres which compromises the 0-60 badly. 30-70mph in these cars with 400+ ft/lbs of torque produces performance you are unlikely to have experienced before unless you are a biker! :mrgreen:

As for 165mph, possible but the issues there will be the screen bending plus the sheer noise of the wind will make it very unpleasant so earplugs advisable! However I know my car was still pulling like a train over the finishline at 113mph, and (annoyingly) that was changing from 3rd-4th right on the finishline so another gear to go.

If you want my humble opinion, unless you are truly into racing, (Colin was running high 11's in his 500hp LS GD), once you are over 400hp in a car this light, you've really got all the power you would ever need on a road. The extra 100hp will be very expensive in parts and will make your car much less fun to drive in most road situations. You're going to need heads with higher volume runners 210cc+? a semi race cam etc... Not saying don't go for it, just do it with all the pitfalls known and accepted... :-D

ajcav86
29-06-12, 08:24 PM
Hi i am with Craig with the same set up and i find you can program the right set up for your driving ability , anything from mild to completly wild , almost undrivable on the highway, but ok for track, Dave B

when you say you can program the set up.. does that mean you alter the amount of BHP or performance? Just wondering how it works? Does it mean you could dial your car down to 400bph for road and up to 500 for track for arguments sake? I am learning fast here but still so much to learn lol

britbits
29-06-12, 09:04 PM
my car currently is mapped to a max 4,500rpm which gives me driver ability on the road and good fuel economy, if i were to race with this set up i would starve the engine of both fuel and air therefor resulting in an engine siezure, so a map for higher rpm would require more of both air and fuel,running the car with my set up now gives an allround good performance, 1,800 to 2,000 rpm = 70mph and delivers 24mpg, i don't drag or race that often now, Dave B

ajcav86
29-06-12, 09:13 PM
my car currently is mapped to a max 4,500rpm which gives me driver ability on the road and good fuel economy, if i were to race with this set up i would starve the engine of both fuel and air therefor resulting in an engine siezure, so a map for higher rpm would require more of both air and fuel,running the car with my set up now gives an allround good performance, 1,800 to 2,000 rpm = 70mph and delivers 24mpg, i don't drag or race that often now, Dave B

But all your saying is that you could drive to the track, plug your laptop in, race, laptop again then drive home? Or have I miss understood the technology?....

Thanks for all the feedback btw really appreciate how friendly and helpful everyone is in the Cobra world!! :-)

V8 BJC
29-06-12, 09:23 PM
Hi Lex and Welcome,
My car originally had a 383 in it with Edelbrock RPM Performer kit. Was great fun with awesome power when needed but lazy road manners when not. Not sure on the power it was making but certainly sub 440.

I now have a 400ci Dart SHP Block with Dart Pro 1 heads which produces 500bhp. Would easily do more if I changed my single plane vic jnr intake to a dual plane but I can't fit that under my bonnet as I have an original style small scoop rather than the
Dax wide one. Even with 500bhp when you want it, the car is is so easy to drive with good road manners at slow speeds. The thing to get right is cam choice. Avoid the temptation to go for more radical cams to achieve peak power, for road use you don't need it and fot the limited time you get on track it does not feel lacking in any way. I had my car on the top gear track last weekend and it is a lot of fun.

Enjoy your research and build.

Brian

as is. unless you really want a track carno - just let the torque go for milder cams and

britbits
29-06-12, 09:26 PM
you can store as many diferent map settings on your computer as you wish, one for every type of track, and or weather conditions , as long as you retain the basic set up, and you can map from the passenger seat while driving ,or rolling road, your choice.

KevinW
30-06-12, 01:55 AM
Just a suggestion, and I know abs nothing about injection, but, if you are up to £40k as a budget already, which is a very healthy one, you might want to just consider what you might get back on your car should you sell it. If £££££ doesnt matter, then no matter, but it was one of the reasons I sold my last rather modest car, as I knew I wouldnt see the extra few £k back on it that I was thinking of spending.

ajcav86
01-07-12, 11:31 AM
We have decided on a Dart 400ci with TWM EFi... 500BPH... However I read the Dax exhausts aren't very good and on 500HP I could loose 100HP... Something about them not having proper collectors.. Has anyone experienced this/know of good alternative pipes?.... Or has this been fixed?..

slogger
01-07-12, 12:26 PM
We have decided on a Dart 400ci with TWM EFi... 500BPH... However I read the Dax exhausts aren't very good and on 500HP I could loose 100HP... Something about them not having proper collectors.. Has anyone experienced this/know of good alternative pipes?.... Or has this been fixed?..

What do you mean by 'Not having proper collectors'?

I think you will find the power loss is due to the smaller baffle tubes and cones used to reduce noise for IVA. 2 inch I think but you can change these for a 3 inch option or bigger should you have them fabbed yourself. I suspect if these tubes are to big, then you may start to loose power and torque, but I'm no expert in this field.

40K budget! I'm surprised you are building a Dax even though you can't go far wrong with them.

ajcav86
01-07-12, 12:29 PM
What do you mean by 'Not having proper collectors'?

I think you will find the power loss is due to the smaller baffle tubes and cones used to reduce noise for IVA. 2 inch I think but you can change these for a 3 inch option or bigger should you have them fabbed yourself. I suspect if these tubes are to big, then you may start to loose power and torque, but I'm no expert in this field.

40K budget! I'm surprised you are building a Dax even though you can't go far wrong with them.

Why are u surprised were building a DAX? What would u be doing?...

Lloyd Barnes
01-07-12, 12:31 PM
Think OP is referring to them having proper merge collectors which do have a significant impact on power. I didn't use the Dax exhausts on my car so can't comment but sure I have read elsewhere on here that this is true.

Plenty of places will make you a custom exhaust if you don't mind paying (and it seems you don't). Noise as said needs to be a consideration in designing them though, particularly as you intend to do track days.

ajcav86
01-07-12, 01:07 PM
Think OP is referring to them having proper merge collectors which do have a significant impact on power. I didn't use the Dax exhausts on my car so can't comment but sure I have read elsewhere on here that this is true.

Plenty of places will make you a custom exhaust if you don't mind paying (and it seems you don't). Noise as said needs to be a consideration in designing them though, particularly as you intend to do track days.
Any ideas where to go for a good exhaust then? And are there things you can put on the exhausts for track days?

shadow
01-07-12, 02:13 PM
Why not stick to a 350 sbc, 8.1 compression EFI and add a procharger?! Been done befor with staggering results! With your budget that's a healthy option!

Lloyd Barnes
01-07-12, 02:15 PM
The guy who made mine went bust sadly so i cant recommend anyone Perhaps others have had exhaust made and can advise.

I remember someone on here had nuts welded into the end of their side pipes, onto which a perforated plate was screwed to reduce noise. I imagine it also reduced power considerably but at least it was removeable for the road.

aaronjb
01-07-12, 02:35 PM
Any ideas where to go for a good exhaust then? And are there things you can put on the exhausts for track days?

Given your location, these folks are probably a good place to start - they've been highly recommended to me, though are probably outside my price range: http://www.simpsonraceexhausts.com/

craggle
01-07-12, 02:37 PM
Nothing wrong the Dax pipes if you like the look of them, They are a fair bit bigger and look different to the original Cobra side pipes.

I think the issue was that Dax fit 2" perforated tube as standard to reduce noise for the IVA, They do after all, have to sell IVA compatible parts.
The 4 headers come together into a collector that is 4" round which is smaller than the full 5" diameter of the side pipe then the gases then get funnelled down into a 2" pipe. Way I understand it is the gasses come out the headers at high speed, then expand and slow down to fill the larger side pipe section just after the collector, then the gasses have to accelerate again down the 2" pipe. That can take power away from the engine apparently but I doubt 100bhp is realistic.

I modified my pipes by changing the 2" core for a 3" perforated tube and made a funnel on the front of that which goes right up to the header pipes inside the collector. The funnel is now about 6" long and goes from 4" diameter of the collector down to the 3" pipe so the gasses get to flow a lot smoother. Power and smoothness of the power did increase but so did the noise levels! :D
I also changed the tail pipes from 3" to 4" exits just for the fun of it. :)

Good thing with the Dax pipes is they bolt together so you can take them apart and do what you like inside.

Craig.

ajcav86
01-07-12, 02:52 PM
Why not stick to a 350 sbc, 8.1 compression EFI and add a procharger?! Been done befor with staggering results! With your budget that's a healthy option!
Sorry can you translate that into laymans? Any links? :)

ajcav86
01-07-12, 02:54 PM
Nothing wrong the Dax pipes if you like the look of them, They are a fair bit bigger and look different to the original Cobra side pipes.

I think the issue was that Dax fit 2" perforated tube as standard to reduce noise for the IVA, They do after all, have to sell IVA compatible parts.
The 4 headers come together into a collector that is 4" round which is smaller than the full 5" diameter of the side pipe then the gases then get funnelled down into a 2" pipe. Way I understand it is the gasses come out the headers at high speed, then expand and slow down to fill the larger side pipe section just after the collector, then the gasses have to accelerate again down the 2" pipe. That can take power away from the engine apparently but I doubt 100bhp is realistic.

I modified my pipes by changing the 2" core for a 3" perforated tube and made a funnel on the front of that which goes right up to the header pipes inside the collector. The funnel is now about 6" long and goes from 4" diameter of the collector down to the 3" pipe so the gasses get to flow a lot smoother. Power and smoothness of the power did increase but so did the noise levels! :D
I also changed the tail pipes from 3" to 4" exits just for the fun of it. :)

Good thing with the Dax pipes is they bolt together so you can take them apart and do what you like inside.

Craig.
In that case I might do that as I do love the look of their pipes... Heading down there this week so will have a chat with them

shadow
01-07-12, 06:13 PM
Sorry can you translate that into laymans? Any links? :)

Sorry, been on here too long. I too was a newby once.... What I mean is. If you're going for big power and driveability. Get a good engine built with low compression and attach a supercharger!
Normal at idle and cruise with reasonable mph, but give it some revs and automatic boost. it will exceed the bhp you are looking at if the engine is built properly. Depends how much of a monster you want to create. Cheaper to do at the beginning of a build, than to squeeze ever last horse out of a normal 383.
Bit like a turbo but without the lag!

cobracol
01-07-12, 06:46 PM
Lex, you have had some great advice, and almost all i would agree with, hope its helping you choose, rather than adding confusion, by choice im staying well away from EFI, IMHO if you want a car to start first time, be economical and smooth, buy a jap, definately BBC or BBF (big block Chevy or Ford) will affect the handling at the limit, but you are unlikely to experiance those limits on a public road, no reason why a carb cannot be nearly as economical as EFI, and just as, if not more reliable, much cheaper to buy, and your right foot gets to choose what power you want, however if you really want EFI and serious power, AKs white demonstrator has an LS3+ Supercharged engine in it: AK SPORTSCARS - YouTube (http://www.youtube.com/watch?v=vS6kJBXI9Jo&feature=plcp) & Ak dyno run 1 - YouTube (http://www.youtube.com/watch?v=kCEsJBmnHAs) perfect for a run to the shops LOL, but probaly way more power than needed or can be used on public roads