Race built engine - what improvement could be expected?

G

gran racing

Super Moderator
Currently I race with a stock engine that has a lot of miles on it (around 190,000). I also have a parts car / engine that is currently just being stored for a rainy day. I was speaking with someone that builds engines and might be able to work out a barter arrangement to have him build an engine for me. It still would cost me some money, but relatively speaking it would be pretty darn cheap.

How much time could I save by getting a race built engine? (not touching anything else) Based on talking to other Honda people, it seems like it might be possible to gain another 20 HP (not sure if at the wheels or crank).

At this point in time, I am not going to sell my car and get a "real" race car. It simply isn't something that I could sell my wife on. But the barter idea is something she would go for...
 
What kind of engine for what car in what class?

AB

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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region #188967
 
It is for a 1987 Honda Prelude si. Currently classified in ITA.

110 HP stock at crank. Min. allowed weight 2,450 lbs. And I do realize that I still would not be near the front runners in ITA, but it would put me more in the mix of things / possibly more fun. IF it got reclassified in ITB, it might be competitive. I am really basing my decision as if it were to stay in ITA.

As we all know, the 1993 VW Golf 2.0L got moved to ITB. It has 115 HP and min. weight of 2,350 lbs. There are also several other cars that have better weight/hp rating then the prelude. The Prelude was also newly classed this past year, so they might consider it.

For example at LRP (or other tracks), how much time do you think I could cut from my lap time with the extra HP?
 
LRP is a momentum track. I wouldn't think you would see the kind of improvement that you would see at an NHIS or Pocono where power is important.

If you are running a stock motor, 110 crank hp tranlates to roughly 90 wheel hp. I would be that a full-on IT motor could easily net you 20 more wheel hp or about 135 crank hp (all assuming 18% driveline losses).

Only the people who have done it can give you estimates on lap time improvements. That is a rare bird in ITA.

AB

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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region #188967
 
I'm not a Honda guy, but on most engines +10-15% is normal for IT prep. If you get closer to 20% gain, you've either removed a huge engineering fault or you've cheated
biggrin.gif


Now if you want to start, tuning headers, exhausts, electronics...there is more to be had. However you stated only an engine rebuild.

- Bill
 
Remember Bill, we are dealing with Honda's here. The 108hp 1.6l ITA CRX makes 125 at the wheels with all the right parts.

Each engine is different but the Honda's and BMW's seem to be more than the sum of their parts. Not to mention that the Wankel's do great considering you can't do anything internally besides a balance.

Take the car to a dyno and if you like the power, concentrate on the driving.

AB

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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region #188967
 
Originally posted by Bildon:
I'm not a Honda guy, but on most engines +10-15% is normal for IT prep. If you get closer to 20% gain, you've either removed a huge engineering fault or you've cheated
biggrin.gif

Click to expand...

Numbers I've seen for most front running IT cars would show closer to 20-25% gains... And these are legal, but taking full advantage of IT prep rules (i.e.: + 0.5 compression, .040" over, etc...)



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Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX
DJ_AV1.jpg
 
We would love to see a 20% gain. Legally, of course.

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Lesley Albin
Over The Limit Racing
Blazen Golden Retrievers
 
hmmm, perhaps Chris and I should be racing poorly engineered cars so we get a bigger boost from the IT prep
biggrin.gif


- Bill
 
Originally posted by Bildon:
hmmm, perhaps Chris and I should be racing poorly engineered cars so we get a bigger boost from the IT prep
biggrin.gif


- Bill
Click to expand...

You guys are breaking my heart...

Let's see... doesn't an ITC VW make about 75 hp stock? Assuming a 25% improvement with IT prep, that makes about 94hp...

Since a 510 makes 96 hp stock, and I KNOW that it's actually good for about 115hp with IT prep, AND a good VW can whip a good 510 on most days, I kind of have a hard time believing that those ITC VWs aren't making at LEAST a 25% improvement...

I'd be interested to know what a CRX in ITC makes for power... Anyone want to be it has the best wt/pwr ratio of the group???

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Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX
DJ_AV1.jpg


[This message has been edited by Banzai240 (edited February 17, 2004).]
 
DAve, just so you have another data point in ITA, I dynoed my RX-7 on two occasions, on two different dynos. The numbers were identical.

The second time was at Lime Rock after a race. If I recall, my lap times were probably around 1:05, (Never have had the car in the 3s) and the RWHP was 104.

I was just over min weight. The car came stock with about 100-110 SAE hp. So 2390/104= 23 lbs per hp. Pretty sad, actually! (i'm told that closer to 120 is possible with a well built rotary, which would be about 20lbs/hp)

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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]
 
Originally posted by lateapex911:
(i'm told that closer to 120 is possible with a well built rotary, which would be about 20lbs/hp)
Click to expand...

Jake,

With 104 rwhp, assuming at least an 18% parasitic loss, your making 122hp at the flywheel... Now, that's only a 10% gain...

I think you might need to get a new engine builder (no offense, but seriously...), because the rotary numbers I've seen (yes, real numbers) show more on the order of a 20% gain... and that's legal power... You have to step up beyond just an average rotary build to get there, however...

I agree, however, that the RX-7/3/4 need some help in the current crop of ITA cars... We're working on it... We're working on a lot of things right now...




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Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX
DJ_AV1.jpg
 
I can't wait to see what happens with IT cars! I'm really hoping that my car will be moved to ITB - should be on the agenda for the next meeting.

I know someone else that is really hoping for the same results for his '87 MR2.

I know it is a ton of work for SCCA and might create some tension, but think it will be for the best in the long run. But that is a different conversation...sorry.

If I get the engine done, I assume I should (need to) get the ECU modified?

Interesting...the other post in general discussions about buying a front running car. Is there any point (at least in ITA)? Based on that info. and what I've seen, the difference between a top 1/3 pack car and a winner are pretty substantial. So, if I could run mid-pack (ITA or ITB) with my current car & a good engine, is it worth spending all of that extra money to get a few cars closer? I know that's a question we all need to answer for ourselves.
 
Originally posted by gran racing:
I'm really hoping that my car will be moved to ITB...

I know someone else that is really hoping for the same results for his '87 MR2
Click to expand...

I'm sure you are all aware that a move from ITA to ITB is going to involve buying a new set of wheels, because the 6" wheel-width requirement is still there, and is likely to remain there for the forseeable future...

I personally would think that a chance to be more competitive would be worth the trade-off in wheels, but I would be interested to know how most of you who might find yourself in this situation feel about this?

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Darin E. Jordan
SCCA #273080, OR/NW Regions
Renton, WA
ITS '97 240SX
DJ_AV1.jpg
 
Darin,
The 1987 prelude si was newly classified last year in IT. I've spoken with the other people that run the car and none of us have bought 7" wide rims yet. Most of are using 5 1/2" or 6" rims. Guess that is one good aspect of not having much to choose from with 13" rims.
smile.gif


I do have a lead on some 13" x 7" steel wheels, but will wait till I hear how the request goes. Because it was just classified last year and this will be a review after one year of the car running, it might have a shot.

As for other people - I know Jake who runs the MR2 wouldn't be too upset about the change (to say the least). Buying new rims is a small price to pay to be more competitive.

But yes, you definately raise a good point when talking about other cars and reclassifying them. I still believe that the majority would make the sacrifice. Thanks for taking that into consideration.

(sorry for the multiple posts before - don't know what happened)

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Dave Gran
NER #13 ITA
'87 Honda Prelude
 
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